PHVA for Gharial - Zoo Outreach Organization

Transcription

Population and Habitat Viability Assessment (P.H.V.A.)
Workshop for Gharial
REPORT
July 1995
R.J .Rao. D. Basu, S. M. Hasan, B.B. Sharma,
S. Molur, S. Walker, Editors
P.H.V.A. Workshop
16-18 January 1995
Organised by
Jiwaji University, Gwalior
Forest Department of Madhya Pradesh
Sponsored by
Ministry of Environment, Government of India
Facilitated by
Zoo Outreach Organisation/ CBSG, India, Coimbatore
Indian Gharial PHVA Report
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CONTENTS
I.
Report
Executive summary and Recommendations
Population Biology (Modelling) Group Report
Census and Distribution Group Report
Habitat Group Report
Threats Group Report
Trade Group Report
Reintroduction Group Report
Captive Population/Disease Group Report
Education and Awareness Group Report
II.
Supplementary material
List of participants
Inaugural Programme
Workshop Agenda
III. Reference material
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I. Executive Summary and
Reports of Working Groups
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EXECUTIVE SUMMARY
From 16-18 January 1995 a Population and Habitat Viability Assessment (P.H.V.A.) Workshop for Gharial
was held at Jiwaji University, Gwalior. It was attended by an assembly of wildlife field managers, captive
management specialists, gharial researchers, university professors and NGO’s / NGI’s.
Twenty years ago — in 1975 a Crocodile Project was initiated in India. This programme included conservation
of three threatened species of crocodilians, including gharial a species of immense scientific interest. After
two decades of conservation and significant progress, some researchers and wildlife officers felt that the
work lacked a well-defined direction. There were accompanying concerns about the actual success of the
conservation measures so far implemented, and the fate of the species in the near and distant future. Recent
decisions to terminate supplementation of wild populations withdrew active assistance towards recuperation,
of the species. Concerned researchers and managers felt that a systematic assessment of the current status of
the species following the years of harvest, supplementation and other management strategies was necessary
at this time.
After consultation with leading crocodile experts and institutions of the country in states like Orissa, U.P.,
Tamil Nadu and M.P., the PHVA for Gharial was initiated by the School of Studies in Zoology at Jiwaji
University which has been involved actively in research activities and conservation of this species since ten
years. The Madhya Pradesh Forest Department came in as a co-organiser. The Ministry of Environment and
Forests, Government of India agreed to sponsor the Workshop. The Zoo Outreach Organisation/ CBSG,
India agreed to facilitate the Workshop.
Population and Habitat Viability Assessment, developed by the Conservation Breeding Specialist Group,
SSC, IUCN, is a process for assessing extinction risk for a species and for developing management
recommendations to enhance long-term survival. PHVA workshops are conducted in the range area of the
species in collaboration with wildlife agencies of the area. Also included in the PHVA process was an
evaluation of the status of the species in captivity, projected plans for re-introduction, and issues requiring
collaborative research.
In this Workshop issues and concerns of gharial were discussed in a combination of small working group
sessions alternating with plenary discussions. The Working Groups were: Census and Distribution Group,
Habitat Group, Modelling Group, Threats Group, Captive Management and Disease Group, Education/
Awareness/Human Interaction Group, Trade Group, and Reintroduction Group.
The Census and Distribution Group reviewed the information collated by the researchers and field
managers. In the past two decades about 4000 gharial have been released into 12 rivers in four states under
the “Grow and Release’’ programme in which eggs were collected and hatched and hatchlings reared to
sizes which increased the probability of their survival. While there is every indication that this
Programme has made the species secure in certain areas, there was a conspicuous lack of information
in other areas.
This Working Group recommended that the Annual Census be done in every area, using a more
standardised methodology, and taking the help of local people and other volunteers for whom
briefing sessions, and literature would be organised. It was also recommended that a Central
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Coordinating Unit be established which would provide a mechanism for better interaction between
the different states and agencies involved in conservation activities for gharial.
The Habitat Group defined the various components (with particular emphasis on prey availability)
that make up an “ideal” habitat, which constitute the criteria by which suitable reintroduction sites
could be identified in the future. Sites which fall outside protected areas but are felt to be highly
suitable and stable or those which migrant gharials are trying to recolonise, should be protected
under the Wildlife (Protection) Act. International cooperation for better management of
metapopulation is recommended for habitats extending across international borders.
The Modelling Group simulated gharial populations over a wide range of sites and under various
conditions. The three populations — Chambal, Mahanadi and Katheriniaghat—are in different
degrees of stability. The Chambal population is stable and can even withstand a yearly small harvest
for genetic supplementation of other populations if there is need. A review of the Chambal population
is recommended before five years and after collection of some more information. The Mahanadi.
population, while appearing relatively stable, suffers from a larger number of more potentially
catastrophic threats. Extensive studies need to be done on these threats and the population needs to
be thoroughly assessed again before five years with additional data. The Katheriniaghat population
is very small and unstable, and requires continuous supplementation in order to be sustained at all.
Genetic studies for diversity and for variability are crucial for all populations.
The Threats Group identified 10 direct and 8 indirect threats and identified that gharial populations
of Mahanadi River was the most seriously threatened. It was felt that the Ramganga population
least affected by such threats. It was noted that threats to gharial in unprotected areas such as
fishing sand mining, river side cultivation and industrial pollution can be controlled best by education/
awareness activities. It emerged from the Modelling exercise that inbreeding could be a more serious
threat than previously considered.
The Captive Management and Disease Group assessed the ability of existing captive facilities to
breed and rear gharial for future, either for supplementation of wild or for provision to zoos for
exhibition and education. They concluded that all these facilities taken together could generate a
spatial capacity to propagate as many as 4000-5000 animals per year if required. In this scenario, a
coordinated, scientific breeding programme is necessary. The Group recommended that the zoos
holding gharial should create or upgrade gharial enclosures so as to be more educationally relevant
and more mindful of the welfare of the animals. Those zoos which are identified as breeding or holding
units for conservation may be suitably improved.
The Trade Group assessed the request of some agencies for an. opinion on the opening of trade based on
utilisation of Gharial. The Group felt that conservation of Gharial would not be improved by opening of
trade and in fact could be seriously damaging. The Group affirmed other effects of opening trade also, e.g.
that it would convey a wrong signal for conservation of wildlife in general, offend the cultural and religious
sentiments of a large portion of the population, and even contradict Article 5/A of the Constitution of India.
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The Reintroduction Group endorsed the contention of the Census and Distribution Group as well as that
of the Modelling Group that regular supplementation should be maintained without significant reduction.
However, it was felt that the age of the animals when released and the sex ratio may need to be redefined
according to scientific research input. Frequent and consistent monitoring to determine habitats in which
populations had responded favourably to supplementation with captive reared animals is recommended.
The Education Group identified several target groups, including the people who are most affected by
gharial conservation, e.g. fishermen. They suggested methodology suitable for each, target group and
recommended a drastic upgrading of public education with respect to gharial conservation. The PHVA
participants agreed that lack of public education had been a major lacuna in the Crocodile Conservation
Programme.
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AMALGAMATED RECOMMENDATIONS OF P.H.V.A FOR
GHARIAL
General
A National Action Plan should be prepared under the auspices of the central coordinating unit incorporating
sub-plans for each major river system. Comprehensive management plans should be prepared with
recommendations for these areas as well as for Protected Areas that already exist for gharial and these plans
implemented to minimise irreversible limiting factors.
A second PHVA for gharial should be held within three years, after some of the recommendations have been
implemented and more facts about the biology of the species have emerged.
The research base of every range state of Gharial needs to be strengthened and additional resources made
available for this in view of the importance of the species and its habitat. On grounds of logistic advantage
and presence of trained and experienced manpower, the Zoology Department at Jiwaji University, Gwalior
should be encouraged to grow as a National Centre for Gharial research, with Gharial rehabilitation Centre
at Deori (Morena) being revived as a vibrant field research station.
The Government of India, the range states of gharial, and the zoos and captive rearing centres holding
gharial should utilise the occasion of the 20th anniversary of the Crocodile Project to highlight the success
of the project, the need to continue protection of gharial and the importance of gharial to the aquatic ecosystem.
Government of India should mark this anniversary in an elaborate manner, bringing out posters and brochures
reviewing the Project and suggesting future directions.
Population Biology (Modelling)
General recommendations for all three populations:
1. Systematic monitoring of all gharials is to be carried out to record longevity, age of first reproduction, sex
ratio and other basic biology.
2. DNA finger printing is recommended for all populations to better understand the genetic make up and the
effects of population battle neck.
3. If the populations have retained sufficient genetic diversity between them, Katerniaghat and Mahanadhi
populations are supplemented with gharials from Chambal.
4. Effects of threats must be studied in detail so as to reduce the causes and the impact of these threats.
i) Chambal population
1. Subpopulation within the Chambal population must be studied for migration by monitoring their movements
to understand the dynamics of the population.
2. Harvest of eggs should be done giving due consideration to the requirement of other populations. The
Chambal population can withstand a harvest of maximum 500 eggs every year.
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ii) Katerniaghat population
1. Continuous supplementation is recommended to insure viability of the population.
2. Gharial juveniles of minimum age 4 years and above should be released to reduce post release mortality.
3. Monitoring of the juveniles must be carried out once they are released.
iii) Mahanadi population
1. Continuous supplementation of the Mahanadi population over the last 19 years has in fact helped the
population avoid total extinction. Although continuous supplementations were carried out, however, the
population has not stabilized. Even though the simulation model showed no extinctions in the populations,
high degrees of threats can push this population to extinction. Supplementation must continue to be carried
out.
2. Studies on threats and their effects must be made in detail. This will help understand the actual role such
threats play on the dynamics of the population and also help reduce this cause.
Census and Distribution
Annual census must be conducted. Habitat status with respect to basking and nesting sites should be surveyed
at the time of annual census and possible occurrence of changes monitored by compiling habitat field maps.
All participating state agencies should have effective coordination. Annual census by different agencies
should be well coordinated and a permanent central, coordinating unit should be created.
Comprehensive maps showing distribution of gharial (i) historically, (ii) before initiation of the project, and
(iii) current population strength should be prepared and made available to census agencies. These should be
updated on the basis of census results.
A brief brochure dealing with census techniques should be prepared for distribution to the agencies and
individuals associated with the census with the idea of optimising
survey and census techniques. The possibility of making these more accurate can be explored, in workshops
to be conducted periodically.
NGO’s and other interested individuals should be motivated to participate in survey and census work and a
network of participants to conduct annual census of gharial throughout its country wide distribution built up.
A briefing session should be organised in sector levels for all the participants before census.
Habitat
Availabilty/status of habitat be assessed by trained surveyors on the basis of identified qualifiers. Such habitats
outside protected areas which are identified as highly suitable and stable, or those that gharial migrating out
of P. A.’s attempt to recolonise be protected under the Wildlife (Protection) Act.
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Habitat extending across international borders necessitates international cooperation for management of
metapopulations which occur in such habitats. Several important gharial populations are affected by
impediments arising from lack of coordination between India, Bangladesh and Nepal.
Threats
Identify community nesting areas and provide protection to the nests to reduce the risk of predation. As there
are many gharial in unprotected areas, threats such as fishing, sand mining, riverbed cultivation and industrial
pollution can be controlled best by education/ awareness activities.
The computer modelling exercise indicated that a lack of heterozygosity resulting from inbreeding may be a
problem in some populations. Also very little is known about the age structure of the populations. As no
genetic management has been considered in release programmes to date, it is strongly recommended that
managers take cognisance of genetic and demographic factors.
Operation of irrigation and hydro-electric structures should be examined for possibilities in their modification
to facilitate proper Gharial management and the construction of migration routes for river life are incorporated
into the planning of future projects.
Trade
Although there is no significant trade in gharial, it is still important to educate the local people in and around
gharial habitats. This will promote awareness to stop illegal local trade, which takes place from time to time
for non-tannery products such as eggs, meat and medicinal biomaterial. Training of enforcement officers
(customs, local policemen and forest dept.) to help them in identifying derived products should be done.
Although there has been substantial pressure from international bodies for opening up trade in crocodilian
products in line with the conservation strategy of sustainable use, it was strongly felt by the Workshop
participants that opening of trade in India, at least at present, is not justified. It would create unwanted
results which, on balance, would negate any economic or social benefit generated by opening of trade,
especially for gharial.
The requests which have come from within India for opening up of trade in crocodilian products in recent
years stem in part from the surplus animals which exist with different agencies which bred them in anticipation
of need. Zoos and rearing centres should therefore rear only such numbers of gharial as are required for
exhibition or supplementation. In the case of accidental surplus accumulated “in good faith” and not required
for conservation due to unavoidable circumstances, the Government of India may consider undertaking
support of the animals for the rest of their natural lives.
Reintroduction
Releases for supplementation should be made at a standard optimum size. This exercise should be
supplemented with scientific research input accompanied by frequent and consistent monitoring.
Releases must strictly adhere to the accepted norms of release except when there are species-or habitatspecific variables which require different norms.
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As a result of the modelling exercise which was done on. Katerniaghat populations as well as scrutiny of
results of 20 years of supplementation of wild populations with captive reared animals, the view of the
group was that long-term survival of gharial could not be assured without continued supplementation.
Captive Population / Disease Group
Individual identification marking of gharial should be done using a standardised code to facilitate planned
captive breeding. Preparation of a studbook should be carried out and maintained with available gharials in
zoos/gharial rearing centres.
It is recommended to have detailed investigation with the help of disease diagnostic laboratories to come to
definite conclusion about the disease responsible for mortality and to find out the proper prescription for
cure.
Detailed investigation with the help of disease diagnostic laboratories should be carried out to arrive at
definite conclusions about diseases and causes of mortality. Better management practices which include
prophylactic measures may be undertaken as well as proper prescriptions for treatment, developed with
collaboration between veterinary institutions and captive rearing centre’s.
The number of hatchlings to be reared should be decided strictly according to the requirement of the stock
intimated by the concerned authorities responsible for reintroduction programmes,
Rearing procedures for hatchlings should be standardised and these standards strictly maintained to ensure
maximum production of gharials from eggs produced in captivity. Contemporary research has opened up
possibilities of controlling sex ratios of crocodilians produced through temperature controlled incubation.
This technique should be investigated with the objective of improving gharial management in situ through
supplementation if so required.
Education
The PHVA participants agreed that lack of public education had been a major lacuna in the success of the
crocodile conservation programme. It was felt that a major initiative should be directed towards specific
target groups important to gharial conservation, such as fishermen and others who might have been affected
by the gharial programme. Emphasis should be given on the utility of gharial for sustaining the health of the
river system and the perilous consequences of its disappearance.
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MODELLING
Introduction
One method for understanding the factors affecting the population extinction process is to use population
models. A model is a basic tool used to represent or describe, in a simplified and abstract form, a
particular process of interest. In the case of the PHVA, modeling is a tool that mimics the processes, by
which populations propagate themselves from one year to the next.
A Simulation Model: stochastic population simulation model is a kind of model that attempts to
incorporate the uncertainty, randomness or unpredictability of life-history and environmental events into
the modeling process. Events whose occurrence is uncertain, unpredictable, and random are called
stochastic. Most events in an animal’s life have some level of uncertainty. Although we cannot predict
exactly what events an individual will experience during its life, we may have a general idea of the range
of possibilities for these various events. Similarly, environmental factors, and their effect on the
population process, are stochastic - they are not completely random, but their effects are predictable
within certain limits.
A simulation model of an animal population mimics actual demographic and genetic events, such as
deaths and births, in an explicit time dimension. Both time steps and individuals are usually simulated as
discrete and finite. When stochasticity is included in a simulation model, each run may be a unique
sequence of events, with different end results in all runs. So, to be able to present both a reliable expected
average result, as well as an estimate of expected variations in the result, we need to run the simulation
many times, often several thousand times.
Events that are random or stochastic need to be described in terms of both their average value (mean) and
their variance, or standard deviation (a measure of the distribution which values can take around their
mean). The Vortex computer model, which is the one we use for PHVAs, incorporates factors with
uncertain outcomes (stochastic factors) by randomly making a decision about what will happen within the
limits as specified by the variance associated with that factor.
There are a host of reasons for why simulation modeling is valuable for the PHVA process. The primary
advantage, of course, is to simulate scenarios and the impact of numerous variables on the potential of
population extinction.
Population modeling supports consensus and instills ownership and pride during the PHVA process. As
groups begin to appreciate the complexity of the problems, they have a tendency to take more ownership
of the process and the ultimate recommendations to achieve solutions. Modeling also forces discussion on
biological aspects and specification of assumptions, data, and goals. The lack of sufficient data of useable
quality rapidly becomes apparent and identifies critical, factors for further study (driving research),
management, and monitoring. This not only influences assumptions, but also
the group’s goals.
Modeling can be used as a tool to create credibility by using technology that non-biologically
oriented groups can use to relate to population biology and the “real” problems. The acceptance
of the computer as a tool for performing repetitive tasks has led to a common ground for persons
of diverse backgrounds.
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Population modeling explicitly incorporates what we know about dynamics by allowing the
simultaneous examination of multiple factors and interactions - more than can be considered in
analytical models. The ability to alter these parameters in a systematic fashion allows testing a
multitude of scenarios that can guide adaptive management strategies.
Finally, the tool of population modeling can be a neutral computer “game” that focuses attention
while providing persons of diverse agendas the opportunity to reach consensus on difficult issues.
The outcome of population modeling can be of political value for people in governmental
agencies by providing support for perceived population trends and the need for action. It helps
managers to justify resource allocation for a program to their superiors and budgetary agencies as
well as identify areas for intensifying program efforts.
The VORTEX model analyzes a population in a stochastic and probabilistic fashion. It also
makes predictions that are testable in a scientific manner, lending more credibility to the process
of using population modeling tools. This model is designed specifically for use in the stochastic
simulation of the small population/extinction process. It has been developed in collaboration and
cooperation with the PHVA process. The model simulates deterministic forces as well as
demographic, environmental, and genetic events in relation to their probabilities. As do all
models, VORTEX has its limitations which may restrict its utility in some cases. In this PHVA
every attempt was made to compensate for such limitations and create scenarios to reflect the
potential problems of various populations of this species.
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POPULATION MODELLING *
Members: Sanjay Molur, R.J. Rao, D. Basu
The gharial population simulation models were constructed with input from researchers and field
managers working at the gharial sites and rearing centres. Data was also gathered from published
literature before and during the gharial supplementation programme started by the Government of India.
In some cases where old data differed from that of the more recent studies, a consensus was sought from
all the field workers present at the workshop.
Mostly, studies on the Chambal population were taken as a basis on which the biology was worked out.
Models were run on a 386, 486 and pentium IBM compatible processor. VORTEX Version 7 was used to
construct the models.
The gharial populations were identified to survive in three locations, viz: River Chambal, Katerniaghat and
Mahanadi and cases of rare sightings were reported from Ganges, Brahmaputra, Gandak and Narayani rivers.
The Chambal population is the largest with an estimated 1100 individuals. Mahanadi is next with 200
individuals and Katerniaghat finally with 54 individuals. Sightings of “a huge male”, “two females and a
male”, “one gharial of unidentified sex’’ in other rivers such as Ganga and Brahmaputra were reported by a
few researchers. Gharials were once known to inhabit these rivers but have now become extinct. These
rivers, however, could have a few individuals along areas of favourable habitat. Flooding of the Chambal
causes gharials to wash away towards the main river -Ganges. Some individuals that survive the turbulent
waters might have found suitable habitat in parts of Ganges.
Simulation models were run for the three populations of gharials separately.
Basic scenarios
Sex ratio at birth
Studies have indicated that there is a female biased sex ratio at birth in gharials, as in other crocodilian
species. The participants were of the view that it varied from 3 to 5 females to every male. Scenarios were
run with sex ratio 1:4 and 1:3. Low ratio of 1:2 and 1:1 were also tried in certain cases. Temperature regulation
during incubation determined the sex of the hatching.
Life expectancy
There is no record of longevity of gharial in the wild or in captivity. Only one female gharial lived up to 29
years in captivity. The oldest crocodilian in captivity was a mugger that lived up to 45 years. Based on the
participants’ view of life span, a low of 40 years and a high of 80 years were tried in the models. Life
expectancy of gharial according to some participants was more than 100 years.
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* Dr. Seal was kind enough to read a preliminary report of the modeling and suggest corrections for
setting up the model more accurately.
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Age of first reproduction
Captive gharials are known to mature at an earlier age of 8 years for females and 10 years for males.
However, gharials in the wild mature at a later age. Population scenarios were modelled with age of first
reproduction for females at 10 and for males at 13. An additional scenario of lower female age of first
reproduction at 9 was also modelled.
Population studies in Katerniaghat showed gharial to mature at a later stage in that river.
Therefore, in case of Katerniaghat population, a scenario of female age of first reproduction at 13 and for
males at 17 was modelled.
Mahanadi population was modelled more on the lines of Chambal.
Female fertility
All adult females in the breeding pool reproduce every year. Scenarios with 90% and 92% female fertility
were modelled. Breeding records of Gharial from Nepal indicated female fertility rate at 50% annually. This
scenario was modelled in almost all the cases.
Male fertility
Territoriality among male gharials has been noticed and the harem system is rather strict. A very limited
number of males mature from sub adulthood to adulthood. Fierce fighting with rival males usually results in
the death of the weak one or the subdued male moves away from the aggressor. All mature males are known
to breed. Bachelor groups in gharial have not been observed.
Clutch size
A minimum of 15 eggs per clutch to a maximum of 65 eggs per clutch have been observed
in the wild. Eggs collected from the wild and reared at different rearing centres have been recorded. Frequency
of clutch size of 35-45 is the maximum while the frequency of
clutches with over 50 eggs is less.
No. of eggs/clutch
Frequency
16-35
20%
36-45
50%
46-65
30%
For the model, a clutch size of 40 was chosen. A smaller size of 30 was also modelled in
certain cases. One of the researchers in Chambal noted that recently more number of clutches with 55 and
more individuals was recorded. Hence the scenarios were also modelled for 60 eggs per clutch.
Mortality
Juvenile mortality is very high in Gharial. Up to 95% mortality is recorded for juveniles of the age group 01 years. Flooding is the main cause for this mortality. Large clutch sizes make up for the high rates of
mortality. Juvenile mortality up to the age of 4 years is high. Subadult and adult mortality are very low.
Different scenarios were modelled with varying mortality rates. In all the cases 90% mortality for 0-1 age
class was modelled. Standard deviation (SD) for the mortality was entered as 3% for 0-1 age class.
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Catastrophe
Environmental catastrophe such as flooding is the main cause for high mortalities. This phenomenon affects
only the hatchlings and very young juveniles. The young gharial is washed away to tributaries and creeks
where they die due to unfavourable conditions. This factor however is considered in the mortality rates (high
juvenile mortality) and is not modelled as catastrophe.
Untimely and sudden opening of flood gates of check dams along the river is a threat to gharials living
downstream. Predation from humans and dogs are very negligible. Fishing is also negligible and only
accidental. Agricultural practices near river banks is one of the major causes of habitat destruction. All these
factors together constitute a major threat and have been modelled as a single catastrophe. A catastrophe with
a frequency of 10% with varying effect on survival from 10-55% have been modelled.
For the Mahanadi population, a higher effect of catastrophe has been modelled. This is because of egg
collection and high degree of pollution in the river. The model is still conservative as compared to that found
in Mahanadi.
Initial population size
The initial population size for Chambal has been modelled for 1100 (present count) and 100 (number at the
beginning of the gharial supplementation project). The models were constructed with initial number of 100
odd animals to see the effect of management (harvest/ supplement) on the population structure for the last 20
years. Katerniaghat population was modelled at 55 initial population arid Mahanadi at 200 initial populations.
Carrying capacity (K)
According to researchers at Chambal the habitat is still suitable for an increase in gharial numbers. Since
fishing is also minimal, an adequate prey-base is present to hold about 2500 gharials (an estimate that is
more than double of the present numbers).
According to the nesting sites observed over a period of time, the numbers of nests have stagnated for the
last 3-4 years. Some feel that this might be due to the carrying capacity-limit of 1100 the population has
already reached.
Researchers point out that though there is stagnation, the nesting sites have the capacity to hold 12-15 nests
of which they are holding only 4 or 5 on an average at present. The prey-base according to them is also
adequate for more individuals.
The simulations for Chambal were modelled with a carrying capacity of 1000 and 100 as initial population
and with 2500 as carrying capacity to see the effect it had on the population growth. For initial population of
1100, the carrying capacity was 2,500.
Populations of Katerniaghat were fixed a carrying capacity of 100 which was what the researchers thought
the habitat could hold. In the case of Mahanadi, it was set at 500.
Harvest
For the models where populations went extinct in a short period of time, eggs were harvested for rearing.
The supplementation project for gharial that was done for 18 years involved collecting eggs from the wild,
incubating, hatching and rearing them at the rearing centres. When the hatchlings were 3-4 years old, they
were released back into the river. During the last 18 years, the rearing centres developed expertise in rearing
gharial eggs, such that the mortality of the hatchlings was reduced to 40%. Recently, Kukrail Gharial Rearing
Centre (Katerniaghat) recorded 100% success in hatching and rearing gharial eggs.
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In modeling the scenario, a number two and a half times the initial population was chosen as the number of
eggs to be harvested. The model asks for the number of individual to be harvested starting from age 1. Since
the eggs in this case would be considered age ‘O’ the initial mortality of 90% (0-1 age group) had to be
calculated as the computer does that automatically to the individuals in the 0-1 age class. Ten percent of the
actual number was entered as the number of eggs harvested. For example, for an initial population of 100
animals, 250 was the number of eggs to be harvested. Considering 90% mortality only 25 eggs were entered
as being harvested. The scenarios modelled with harvest had the first year, last year and the interval of
harvest entered.
Scenarios were also modelled with harvest not accounting the 90% mortality in one case and in another
accounting just 40% mortality.
Supplementation
The eggs harvested in year one were reintroduced into the natural habitat as 3 or 4 year old hatchlings
during the gharial supplementation programme. Similarly, the scenariosmodelled had supplementation of
3 or 4 year olds into the natural population. Supplementation was started from the third year of first harvest
and continued every year for up to three years after harvest was discontinued.
The reason for harvest and supplementation is to reduce the 0-4 age class mortality. Since the rearing
centres had achieved 60% success, mortality was brought down by more than 35% in total 4 years when
the hatchlings were reintroduced.
In the scenario where 10% of the actual eggs were shown as harvested, a supplementation
of 60% of the actual numbers of eggs was entered. For example of 240 eggs, 24 were shown as harvested,
144 hatchlings were supplemented into the population. This difference is to make up for the decrease in
the mortality rates.
In other scenarios with no mortality included in the harvest and with 40% mortality in the
harvest, supplementation was carried out accordingly.
Inbreeding
Though the Chambal population of 1100 underwent a bottleneck of 107, 20 years ago, the effect of inbreeding
was assumed to be either nil or very low since the average generation time for the species is about 20 years.
Further, no genetic studies have been carried out for gharial to determine inbreeding either in the wild or in
captivity. Therefore inbreeding value was not adopted for the models simulated.
Results and discussion
The scenarios modelled were with the intention to study the population dynamics over the
next hundred years by varying fertility rates, mortality rates, catastrophes, population size, carrying capacity,
without and with management practice; and with a view to understand what best management action plan
needs to he adopted if the population is to survive and retention of more than 90% of heterozygosity.
Chambal population
The scenarios modelled considered the present population structure of gharial and how different variables
incorporated affect the dynamics for the next hundred years. A second set of scenarios considered the population
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20 years ago. This set was also used as a counter check by verifying its outcome with the actual occurrence
in nature. A third set of scenarios were considered that looked at the population 180 years ago and were run
for 200 years to see the effects today. Results of all scenarios are recorded in tables 2 to 4.
Initial population size and carrying capacity
Scenarios modelled according to conditions prevailing 20 years ago had an initial population of 100. Carrying
capacity for this population was fixed at 1000 or 1100 and
run for 20 years. Population with 100 as initial size went extinct in a short time. Carrying capacity of 1000,
1100 or 2500 did not matter to scenarios run without management practices to this population size.
Scenarios with starting population size of 1100 (present status) were modelled with a
carrying capacity of 2500. Parameters for the scenario were chosen on the basis of validity of results obtained
for initial population size of 100 or 107. Populations were also modelled for carrying capacity of 1100.
The scenarios with carrying capacity value of 2500 and initial population size of 1100 showed a very healthy
trend in population growth and stability. The populations that were modelled at initial population already at
saturation stage (n & K = 1100), they remained stable over the long run. The population showing positive
growth rate were truncated at the carrying capacity value.
Mortality
Different rates of mortality were applied to different runs. The 0-1 age mortality was varied between 90%
and 92%. Populations with 92% mortality had a higher probability of extinction in populations of initial size
100, though when seen across different populations, this did not matter much. Similarly, the standard deviation
for the above mortality was entered either as 3% or 21 %. Population with initial number 1100 modelled with
higher SD showed a slower growth rate and those with 100 initial population showed higher rate of extinction.
Mortalities were also varied at different age classes in different scenarios. Populations with mortality rates
higher in sub adult class were subjected to higher extinctions (initial size 100) and slower growth rates
(initial size 1100).
Female fertility rates
Females’ fertility rates were tried at 92%, 90% and 50%. The higher the fertility rate, the higher was the
stochastic growth rate. Much variation was seen in varying fertility rates only in the 1100 initial populations’
scenarios. A distinct decline in the growth rate is seen with decreased fertility rate of 50% (Graph 1).
Populations of 1100 however do not become extinct.
Sex ratio
Populations modelled with lower sex ratio of 1:3 showed a nominal growth rate but retained higher
heterozygosity at the end of 100 years. Populations with higher sex bias of 1:4 showed a higher growth rate
but lost heterozygosity faster. Difference in sex ratio did not matter as much with population of initial size of
100 since either scenario went extinct.
Harvest/Supplementation
Populations of initial size of 100 went extinct in all of the scenarios in 100 years. This population was taken
as a control to test the accuracy of the model. Yearly harvest and supplementation was entered similar to that
carried out in the wild for the last 19 years during the gharial supplementation programme. The scenarios
modelled showed distinct rise in stochastic growth rate during supplementation (Graph 2) and a nominal but
steady growth rate after the supplementation was stopped (Graph 3).
17
Web version
The gharial population of 107 in 1976 would have gone extinct by now or very low numbers of an unviable
population size would have remained today if the management programme had not been implemented.
Results of the scenario indicated extinctions without management.
Results for population size of 1100 indicated no extinctions “without a management programme. The
population of 1100 is large and stable and can even withstand a small harvest every year without
supplementation. Harvested eggs from this population could be used for releases into other viable habitats
or other areas with small gharial populations.
Metapopulation
The Chambal population can be categorised into 3 zones of 109 km, 90 km and 24 km stretches (Fig. 1).
Each of these stretches or zones has gharial populations. The number of gharial is calculated by the number
of nests per nesting site in these zones. There are 15 nesting sites totally with an average of 4-5 nests per site.
The number and sex of gharial was calculated according to the single population count of 1100 and proportion
of adults to subadults and juveniles. The number of nests indicates about 90% of adult females.
The three zones were considered as sub-populations and modelled with migration. Migration downstream
was taken as 5% and upstream as 2% (participants in the workshop). The panmictic population was considered
as genetically one.
Even as different subpopulation, they did not go extinct in 100 years. The Chambal population considered as
different populations still survives well without management practices. Harvest could still be carried out in
small quantities for later release in other habitats.
The Chambal population can be considered either as a single large population or three or five different
subpopulations (Fig. 1). It is not clearly understood whether migration occurs between these populations. It
is speculated that there is migration downstream during floods and upstream when the water level begins to
recede. However, only one case of an adult male fighting with a resident male 28 km upstream has been
observed.
18
Web version
Table 1. Gharial releases in National Chambal Sanctuary during 1979 - 1987
YEAR AND MONTH OF
RELEASE
PLACE
NO.
GHARIAL
1979 - May, November,
December
Jeora
15
60
1980 - March
Barenda
Kenjra
Pureini
15
45
50
110
Kuthiana
Chinnouni
Sahaspura
Baroli
44
83
43
83
253
Deogarh
Nadigaon
Baroli
Rameswar
45
50
49
43
187
Kenjra
Keori
Deogarh
Pureini
24
74
50
50
Pali
Pali
38
30
68
Barenda
Barenda
Barenda
Pali
Rameswar
20
20
20
10
20
90
Udi
Rameswar
Rameswar
Rameswar
1
20
19
20
60
Rameswar
Baroli
Pinahat
Pinahat
Nandagawa
48
50
49
48
42
1981 - March, April
1982 - January
February &
March
1983 - January
1984 - March
1985 - February
1986 - February,
March &
April
1987 - March &
December
Total
19
TOTAL NO.
GHARIAL
75
198
237
1278
Web version
Table 2. Preliminary models for the Chambal population with initial population of 100 and a carrying capacity of
1100. The models were base on management practices (harvest and supplementation). Number of eggs harvested =
30; number of 3 year old gharial supplemented = 100 (80 females and 20 males); varying mortality schedules;
female fertility at 92%, 90% and 50%.
File Name
Sex
Death Ratio
M:F
P.B. Results
CATAS
S.
r
(D)
STOCH ‘r’
W/H
PE% N
SD
H
TE
WO/H
R
SD
R
SD
Ghar_020
80
1:4
1
.060
50.4
302 272.7 73..8
54
-.0836
.4043
.0295
.7963
Ghar_022
80
1:4
1
.060
16.6
313 276.8 82.4
130
.1435
.4504
.0306
.7876
Ghar_030
80
1:4
1
.060
14.4 308 295.5 82.1
123
.1507
.5166
.0309
.7884
Ghar_031
80
1:4
1
-.023 99.8
86
.0763
.5109
-.0649
.8755
Ghar_033
40
1:4
1
.076
16.4 310 289.1 79.9
122
.1638
.5561
.0415
.8454
Ghar_034
40
1:3
1
.072
6.0
365 332.4 91.1
90
.0590
.8988
.1579
.6177
Ghar_035
40
1:3
1
.072
0
988 135.4 95.8
-
.1599
.2705
.0712
.2464
Ghar_040
40
1:3
1
.072
0
1049 85.8
99.7
-
.1703
.2586
-
-
Ghar_041
40
1:3
1
.072
0
990 135.1 95.8
-
.1739
.2013
.1713
.2471
Ghar_042
40
1:3
1
.078
0
1046 91.2
99.6
.1736
.1997
-
-
Ghar_043
40
1:3
1
.058
0
1057 75.6
99.7
.1643
.1750
-
-
Ghar_044
40
1:3
.55
.012
0
903 221.3 99.7
.1297
.2188
-
-
Ghar_045
40
1:3
.90
.048
0
1045 89.4
99.7
.1555
.1783
-
-
Ghar_046
40
1:3
.90
.042
0
1042 87.5
99.7
.1522
.1754
-
Ghar_047
40
1:3
.90
.047
0
1043 92.2
99.7
.1595
.1842
-
-
Ghar_048
40
1:3
.90
.035
0
1043 85.5
99.7
.1526
.1787
-
-
Ghar_050
40
1:3
.90
.036
0
1044 87.9
99.7
.1464
.1752
-
-
Ghar_051
40
1:3
.90
.036
0
964 138.2 98.3
.1455
.1789
.0358
22
20
0
70.8
-
.2108
Web version
Graph 1. Chambal population. Stochastic growth rate and female fertility at clutch sizes 30
and 40. female fertility at clutch sizes 30 and 40.
Graph 2. Chambal population. Stochastic growth rate and
clutch size at 40 and 80 years with harvest and supplementation.
21
Web version
FILE
NAME
SEX
CATAS
RATIO
S.
DEATH M:F
P.B. RESULT
INI
POP
K
STOCH ‘r’
W/H
r
WO/H
(D)
PE%
N
SD
H
r
SD
r
SD
Clutch size 40, female fertility 92%, mortality at 0-1 age class 90%
Ghar_241
40
1:3
1
100
1100
.072
0
985
142.9
95.8
.1494
.3318
.0714
.2471
Ghar_242
40
1:4
1
100
1100
.075
0
988
135.9
94.9
.1494
.3383
.0748
.2511
Ghar_243
80
1:3
1
100
1100
.075
0
998
136.2
95.9
.1498
.3322
.0749
.2482
Ghar_244
80
1:4
1
100
1100
.078
0
990
135.8
94..9
.1494
.3333
.0777
.2520
Ghar_245
40
1:3
1
100
1100
.057
0
992
129.8
96.6
.1378
.3083
.0570
.2311
Ghar_246
40
1:4
1
100
1100
.068
0
980
141.0
96.0
.1383
.3118
.0596
.2356
Ghar_247
80
1:3
1
100
1100
.062
0
976
133.7
96.7
.1381
.3081
.0618
.2321
Ghar_248
80
1:4
1
100
1100
.065
0
990
139..2
96.0
.1389
.3128
.0646
.2346
Ghar_249
40
1:3
1
100
1100
.094
0
994
141.1
94.2
.1665
.3638
.0938
.2682
Ghar_250
40
1:4
1
100
1100
.098
0
1005 131.3
92.7
.1654
.3729
.0975
.2722
Ghar_251
80
1:3
1
100
1100
.096
0
983
145.3
94.1
.1660
.3665
.0955
.2693
Ghar_252
80
1:4
1
100
1100
.100
0
990
149.4
92.8
.1671
.3681
.0986
.2722
Ghar_401
40
1:3
,90
1100
2500
.048
0
2260 290.0
99.0
.0475
.2075
Ghar_402
0
2210 299.0
98.8
.0491
.2124
40
1:4
.90
1100
2500
.051
Ghar_403
40
1:3
.90
1100
2500
.047
0
2152 345.9
99.0
.0421
.2080
Ghar_404
40
1:4
.90
1100
2500
.050
0
2179 307.3
98.8
.0452
.2086
Ghar_405
40
1:3
.90
1100
2500
.033
0
2162 335.0
99.2
.0311
.1926
Ghar_406
40
1:4
.90
1100
2500
.036
0
2183 301.9
99.0
.0337
.2013
Ghar_407
40
1:3
.90
1100
2500
.032
0
2142 319.4
99,2
.0296
.1955
Ghar_408
40
1:4
.90
1100
2500
.035
0
2199 298.2
99.0
.0336
.1990
Ghar_409
Ghar_410
40
40
1:3
.90
1100
2500
.018
0
2057 376.4
99.3
.0160
.1769
1:4
.90
1100
2500
.021
0
2143 336.7
99.1
.0195
.1845
Ghar_411
40
1:3
.90
1100
2500
.004
0
1352 580.5
99.1
.0020
.1639
Ghar_412
40
1:4
.90
1100
2500
.007
0
1605 548.1
99.1
.0053
.1682
22
Web version
Table 3. FACING PAGE. Chambal population. Age of first reproduction 10 (females) and 13 (males);
harvest of 180 eggs every year for 20 years and supplementation of 100 eggs every year for 20 years,
starting from the third year of first harvest (harvest and supplementation in files 241 to 252 only)
Table 4. Chambal metapopulation. Female AFR = 10; male AFR = 13; Initial population size (carrying
capacity K) in the first set of tables (3 sub populations, files 001 to 004): pop. 1 = 450 (1050); pop. 2 =
550 (1250); pop. 3 = 150 (350); migration rate: upstream = 2% and downstream = 5%.; Initial
population size (carrying capacity K) in the second set of tables (5 sub populations, files 011 and 012):
pop. 1 = 300 (680); pop. 2 = 150 (350); pop. 3= 80 (180); pop. 4 = 470 (1070); pop. 5 = 150 (350);
migration rate: upstream = 2% and downstream = 5%
FILE
NAME
DEATH
SEX
RATIO
CATAS.
S.
STOCH 'r'
r
META POP. RESULT
(D)
PE%
N
SD
H
r
SD
3 populations, clutch size 60, female fertility 92%, mortality at 0-1 age class 90%, migration 5%
downstream and 2% upstream
Met~001
Met~002
.083
2333
232.8
1:4 3. Chambal
1
0
Graph
population.
Stochastic
growth 97.8
rate and.0882
size at 401 and 80
.081years 0without
2329harvest
257.1and supplementation.
97.8
.0873
40 clutch 1:4
Met~003
80
1:3
1
.058
0
769
115.8
98.0
.0744
.2456
Met~004
40
1:3
1
.055
0
2224
285.5
98.7
.0576
.1589
80
.1718
.1733
5 populations, clutch size 40, female fertility 92%, mortality at 0-1 age class 90%, migration 5%
downstream and 2% upstream
Met~011
80
1:4
.90
.062
0
2219
237.1
98.1
.0667
.1311
Met~012
40
1:4
.90
.058
0
2183
203.6
98.1
.0631
.1323
23
Web version
Graph 3. Chambal population. Stochastic growth rate and
clutch size at 40 and 80 years without harvest and supplementation.
Recommendations
1.
Although the Chambal population has been studied extensively and for a long time, some
of the basic biology is lacking still. Systematic monitoring of all gharials is crucial to know
longevity, age of first reproduction and sex ratio.
2. Threats to the population are in the form of floods, agricultural practices, predation, fishing, etc. These
must be studied in detail to understand the actual damage caused to the population. Such an understanding
could be better quantified for simulation modelling.
3. The scenarios modelled with migration show no extinction. To understand completely the dynamics of
the population, migration studies need to be carried out in detail.
4. The Chambal population seems to have stabilized, and is growing presently. However, to be able to better
predict probabilities, monitoring and study of these populations and their movements will help in better
understanding the dynamics.
5. According to the model, the population is now stable enough to withstand selective harvesting of up to
500 eggs every year for rearing and further releasing at alternate sites.
6.
Gharial population upstream and those downstream may be quite close genetically
because of the bottleneck the population underwent 20 years ago, and this needs to be
verified by genetic testing. DNA fingerprinting is recommended for all the subpopulations
to better understand genetic make up and gene flow.
24
Web version
Katherniaghat Population
The number of individuals in the Kathernaighat population was recorded as 54 in 1994. This figure was
maintained in all the scenarios modelled.
Sex ratio
The population as studied indicate a sex ratio of 1:3 and above, being biased towards females. The sex ratio
seems to play a role in the growth rate and the viability of the population. Though the deterministic growth
rate increases with increased proportion of female to males (1:4), the population does sot seem to sustain
itself for 100 years. The probability of extinction is higher in the higher female biased ratio of 1:4 as compared
to 1:3 (Graph 4), The amount of heterzygosity retained is also higher in a population of 1:3 ratio rather than
1:4 (Graph 5).
Age of senescence
Scenarios were modelled for ages 40 and 80. The populations clearly did well with longer
life span. The growth rate also has a positive increase with longer life span. Probability
of extinction is higher in scenarios modelled with life span as 40 as compared to 80 (Graphs
6,7).
Carrying capacity
Two scenarios of carrying capacity were tried on the Katerniaghat population. The initial
population size was retained at 55 but a carrying capacity value of 100 and 150 were
modelled. The results showed that the population growth and stability depended on the habitat capability
and therefore showed a greater chance of survival with carrying capacity at 150 as compared to 100 (Graphs
8, 9).
Catastrophe
The scenarios were modelled with and without catastrophe. Populations with a low catastrophe of frequency
10% (occuring once every 10 years) having no effect on reproduction but a .9 effect on survival (i.e. 10%
casuality) had a higher probability of extinction compared to those populations modelled without catastrophe.
All of the scenarios were modelled with age of first reproduction for females as 13 and for males as 17.
Extensive studies and observations at Katherniaghat have led to this conclusion.
Unlike other populations such as in Chambal and Mahanadhi where the age of first
reproduction is 10 and 13 in females and males respectively, the Katherniaghat population with its small
numbers is even more influenced by the late ages of first reproduction.
Fertility
Three parameters have been used for the Katerniaghat population. The first scenario had 92% females
producing eggs, second scenario of 90% females producing eggs and third scenario of just 50% females
producing eggs.
The population is very sensitive to very mild changes in fertility rates. Reducing female fertility by 2% (from
92% to 90%) had an effect on growth rate (stochastic ‘r’) which reduced and the probability of extinction
25
Web version
increased. Populations with 50% female fertility went extinct in 40 years when the life span was modelled at
80 years and in 15 years when life span was modelled at 40 years.
Clutch size
There different values for clutch size were modelled. Populations modelled with 60 eggs per clutch did
extremely well. Clutch size of 40 showed a nominal growth rate when catatstrophes were nil (Graph 10).
With a mild catastrophe of frequency 10% and .9 effect on survival, populations modelled with 40 years life
span and clutch size of 60, 40 or 30 showed a negative trend in growth. Catastrophes occuring once in ten
years such as was modelled have a greater effect on populations with a smaller clutch size. When these
populations of smaller clutch size were compared with the scenarios with no catastrophes there was a distinnct
difference in the probability of extinction (Graph 11).
Mortality
Three sets of mortalities were modelled
1) Low mortality after age 4
2) Low mortality after age 4 but higher 0-1 age mortality.
3) High mortality with 90% & 92% mortality at 0-1 age class.
The first two cases of low mortality after age 4 was with 10% (3 SD) from class 4-5. The
second set varied slightly with 92% mortality at 0-1 age class instead of 90%. The third set of high mortality
had a set of values that reduced slightly for every age class beginning at 90%.
Regardless of the type of mortality, all populations went extinct as modelled. Populations modelled with
higher mortality throughout and higher mortality at 0-1 age class (92%) had a higher probability of extinction.
Harvest/Supplement
The population at Katherniaghat is very small to sustain, itself in the long term. The models however
conservatively constructed showed the populations to go extinct in a very short time -15 to 40 years depending
on the longevity of gharial.
The gharial supplementation project by the government of India helped to conserve and aid growth of
Katherniaghat population. The low numbers were able to sustain themselves due to continuous harvest and
supplementation for the past 19 years (Table 5)
In the scenarios modelled, 100 eggs were harvested, according to the last year harvest values (table above).
The value was entered as 10 (including 0-1 age mortality of 90%). The harvest was modelled every year for
50 years.
Supplementation figures were entered as 40 individuals (juveniles) 4years old released every year from the
4th year to 54th year. The ratio of individuals released depended on the ratio of the sexes in the population.
The figure of 40 was to indicate 40% survival in the rearing centres. Although 60% success rate has been
achieved in the centres, a mortality of 20% was considered during transportation & actual pre- and postrelease mortalities
The models were all run for 100 years and with harvest and supplement for 50 years. The populations
remained stable as long as this was carried out but went extinct in a short time thereafter (Table 8). Probability
of extinction varies for models with varying basic scenario but on the whole extinction of the Katherniaghat
population is imminent if no management action is taken.
26
Web version
Probability of extinction was seen to be very high for bigger clutch sizes by the hundredth year. However, the
mean population size remained big for these populations. Stochastic growth rate was faster for populations
modelled with bigger clutch size. Populations with higher sex ratio also showed higher probability of extinction
(Graphs 12 - 19).
Graph 4. Katerniaghat population. Sex ratio and stochastic growth rate
for different clutch sizes with catastrophe of 10% frequency
and .9 effect on survival.
27
Web version
Table 5. Katerniaghat population. Harvest and supplementation carried out during the last 19 years.
CENSUS RESULTS
YEAR AD.
MAL
E
AD.
SUB
FEAD.
MALE
WILD PRODUCTION
JUV. TOT. NO.
OF
POSS.
NEST.
NO.
NO.
OF
OF
EGGS EGGS
HARV
.
210
38
1975
1
5
5
3
14
5
1976
2
8
6
12
28
8
336
1977
2
8
8
14
32
8
1978
2
9
9
14
34
1979
2
8
12
10
32
1980-
NO.
OF
EGGS
LEFT
CLASS-WISE
SUPPLEMENTS
HATL.
SURV.
@5%
AD.
AD.
SUB. JUV.
AD.
MALE FEMALE
172
9
-
-
-
-
215
121
6
-
-
-
-
336
166
170
9
-
-
-
-
9
378
171
207
10
-
-
-
-
8
336
234
102
5
-
-
14
-
96
4032
2128
1904
95
1
-
163
-
1987
1988
2
16
19
4
41
10
420
312
108
5
-
-
-
-
1989
3
25
5
3
36
15
525
200
300
15
-
-
-
-
1990
4
27
5
3
39
15
525
70
455
23
-
-
-
-
525
65
455
23
-
-
-
180
1991
1992
3
27
5
4
39
15
525
-
525
26
2
11
-
40
1993
3
28
4
7
42
15
525
120
405
20
2
11
-
-
1994
5
28
18
3
54
15
28
Web version
Table 6. Katerniaghat population. Single population
FILE
NAME
DEATH
SEX
RATIO
CATAS.
P. B. RESULT
TE
r
(S)
SD
r
PE
%
N
SD
H
Clutch size 60, female fertility 92%, mortality at 0-1 age class 90%, K = 100
Kath~006
80
1:4
1
.058
82.2
69
29.0
45.3
75
.0270
.4021
Kath~007
80
1:4
.9
.048
87.2
67
30.4
45.7
66
.0139
.4019
Kath~008
40
1:4
1
.052
85.2
62
30.7
41.4
73
.0161
.4071
Kath~009
40
1:4
.9
.042
92.0
50
29.8
31.6
65
-.0013
.4130
Kath~010
40
1:3
1
.049
65.8
51
30.1
46.3
92
.0239
.3778
Kath~011
40
1:3
.9
.039
78.8
57
30.7
40.3
85
.0097
.3807
Kath~012
40
1:4
1
.022
65.8
61
27.3
51.2
93
.0053
.2997
Kath~013
40
1:4
.9
.012
90.6
52
27.3
46.4
80
-.0121
.3144
Kath~057
40
1:4
.9
.010
84.0
43
28.0
61.9
43
-.0284
.3888
Kath~060
40
1:3
.9
.008
72.6
35
23.7
63.1
53
-.0230
.3865
Kath~066
40
1:4
1
.011
83.6
43
27.4
62.3
43
-.0276
.3902
Kath~069
40
1:3
1
.009
71.6
40
26.5
64.0
53
-.0209
.3866
Kath~058
40
1:4
.9
-.006
88.6
25
20.7
62.2
47
-.0369
.3619
Kath~061
40
1:3
.9
-.008
85.2
25
19.3
64.1
53
-.0372
.3573
Kath~067
40
1:4
1
-.005
87.2
30
22.7
65.2
46
-.0381
.3602
Kath~070
40
1:3
1
-.007
81.8
24
19.3
63.5
53
-.0341
.3584
Kath~059
40
1:4
.9
-.017
96.4
18
14.8
56.4
44
-.0484
.3456
Kath~062
40
1:3
.9
-.019
93.8
12
7.1
59.7
50
-.0479
.3418
Kath~068
40
1:4
1
-.016
94.6
19
17.5
57.2
43
-.0473
.3435
Kath~071
40
1:3
1
-.018
93.2
15
13.5
64.9
50
-.0460
.3407
29
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Graph 6. Katerniaghat population. Probability of extinction at different age of senescence.
Graph 7. Katerniaghat population. Probability of extinction at different age of senescence for sex ratios
1:4, 1:3 and 1:2 comparing with and without catastrophe
30
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Graph 5. Katerniaghat population. Sex ratio in relation to heterozygosity retained at 100 years for
different clutch sizes and catastrophe of 10% frequency and .9 effect on survival.
Graph 8. Katerniaghat population. Probability of extinction at different carrying capacity values and
clutch sizes modelled at age 40 with 1:4 ratio.
31
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Table 8. FACING PAGE. Katerniaghat population with harvest and supplementation.
Initial size = 55; carrying capacity = 100; harvest programme carried on for 50 years with 10 eggs
removed every year; supplementation for 50 years starting from the fourth year of first harvest, 40
juveniles of 4 years of age (32 females and 8 males when sex ratio of population is 1:4 and 30 females
and 10 males when sex ratio is 1:3) added every year. A result of population behaviour is recorded at 16
and 46 years after the supplementation programme is stopped.
CAT
DEATH
r
P.B. RESULT
70 YEARS
STOCH 'r'
100 YEARS
PE N SD
H
PE% N SD
%
W/H
H
T.E
r
WO/H
S.D
r
S.D
Kathar-1
80
1:4
.90
.024
7
64
27.6
92.5 39.0
57
27.5 86.9
79
.1795
.1637
.0096
.3760
Kathar-2
40
1:4
.90
.014
27
67
25.7
85.3 34.6
51
29.4 81.8
81
.1797
.1880
.0027
.3767
Kathar-3
40
1:3
.90
.011
15
68
24.7
93.1 24.6
51
27.0 83.7
83
.1809
.1731
.0023
.3707
Kathar-4
80
1:3
.90
.022
15
67
25.9
93.1 19.2
63
27.1 85.0
82
.1828
.1653
.0154
.3589
Kathar-5
40
1:4
.90
.032
13
65
30.0
90.9 42.0
54
30.6 79.7
66
.1801 .2367
.0105
.4515
Kathar-6
80
1:4
.90
.038
4
57
30.8
90.7 39.8
63
26.6 80.7
77
.1817
.0031
.0180
.4607
Kathar-7
40
1:3
.90
.029
9
60
28.3
91.5 28.0
56
29.6 80.1
78
.1860
.1738
.0133
.4340
Kathar-8
80
1:3
.90
.036
6
62
26.1
91.1 28.0
66
29.8 81.9
81
.1854
.1828
.0213
.4339
Kathar-9
40
1:4
.90
.006
0
65
26.7
92.7 37.0
43
25.5 85.9
-
.1780
.1943
-.0002 .4092
Kathar-10
80
1:4
.90
.017
5
64
27.7
92.7 18.0
54
24.6 86.4
73
.1801
.1811
.0063
.4071
Kathar-11
40
1:3
.90
.003
2
58
26.0
93.2 38.0
42
27.8 81.8
83
.0025
.1805
-.0066
.4218
Kathar-12
80
1:3
.90
.015
3
62
23.2
92.7 22.0
54
27.8 85.7
81
.1804
.1848
.0092
.4135
Kathar-13
40
1:4
.90
.002
1
71
24.6
93.7 29.0
48
26.8 83.8
83
.1770
.1554
-.0037
.3412
Kathar-14
80
1:4
.90
.014
2
71
24.0
93.6 18.0
61
24.5 86.4
79
.1784
.1595
.0088
.3266
Kathar-15
40
1:3
.90
0
2
68
26.0
93.4 26.0
44
24.8 83.5
86
.1785
.1547
-.0061
.3438
Kathar-16
80
1:3
.90
0.12
4
69
24.0
93.9
64
27.3 86.7
79
.1790
.1554
.0084
.3395
16.0
Kathar-17
40
1:4
.90
-.022
3
68
19.4 95.1
28.0
27
16.0 84.6
88
.1748
.1563
-.0249
.3277
Kathar-18
80
1:4
.90
-.004
3
71
22.3 95.2 23.0
4
23.3 89.8
81
.1749
.1501
-.0053
.3245
Kathar-19
40
1:3
.90
-.024
0
66 22.0 95.7 27.0
28
19.8 85.9
87
.1721
.1611
-.0265
.3233
Kathar-20
80
1:3
.90
-.005
2
70
51
24.2 89.1
80
.1743
.1578
-.0044
.3238
23.0 95.4
13.0
Kathar-21
80
1:4
.90
.004
6
65
26.1
94.6
41.0
44
25.3 84.9
89
.1751
.1570
-.0044
.3290
Kathar-22
40
1:4
.90
-.003
5
62
23.3 93.9
48.0
38
19.6
86.0
83
.1783
.1502
-.0101
.3245
Kathar-23
80
1:3
.90
0
5
69
27.4 95.1
42.0
37
19.7
85.8
75
.1734
.1593
-.0100
.3222
Kathar-24
40
1:3
.90
-.024
3
59
22.2 94.7 50.0
29
17.4
87.1
80
.1760
.1550
-.0301
.3231
32
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Graph 9. Katerniaghat population. Probability of extinction at different carrying capacity values and
clutch sizes modelled at age 40 with 1:3
ratio.
Graph 10. Katerniaghat population. Probability of extinction at different clutch sizes
comparing ages 40 and 80.
33
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Graph 11. Katerniaghat population. Probability of extinction at
different carrying capacity values and clutch sizes modelled
at age 40 comparing values with and without catastrophe
Graph 12. Katerniaghat population. With harvest and supplementation.
Probability of extinction at 16th and 46th year after the last supplementation
modelled for age 40, ratio 1:4 and fertility 92%.
34
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35
Web version
Stochastic growth rate post supplementation as compared with female fertility and
clutch sizes for populations modelled at age 80
36
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Stochastic growth rate post supplementation as compared with female fertility and
clutch sizes for populations modelled at age 40
Probability of extinction post supplementation as compared with female fertility
and clutch sizes for populations modelled at age 40
37
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Probability of extinction post supplementation as compared with female fertility
and clutch sizes for populations modelled at age 80
Recommendations
1.Continuous supplementation should be carried out for the Katemiaghat population since
the number of individuals are too small to be viable on their own. The carrying capacity of the habitat is also
small for the population to remain stable once the numbers reach that.
2. Scientific monitoring of the population must be carried out once the juveniles are
released.
3. Genetic studies of the population should be made to assess the degree of inbreeding the
population has undergone. Genetic typing of certain identified individuals representing different age classes
should be carried out.
4. If the population is not mixed with releases from Chambal or Mahanadhi, genetic affinity must be tested
and such releases should be made to retain enough heterozygosity
5. Hatching and rearing gharial young in the rearing centres has reduced mortality dramatically. Releasing
younger juveniles results in high mortality in the wild. To avoid this, gharial of age 4 years and above should
be released.
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Mahanadi Population
Initial population size and carrying capacity
The Mahanadi population was modelled at an initial population size of 200 based on the estimated number
in the wild. All scenarios were modelled with a carrying capacity of 500 as suggested by the participants.
Age of first reproduction for males was kept at 13 and that for females was modelled at 10 and 9. The value
of 9 was tried because researchers from Mahanadi felt that the females matured earlier by a year. The scenarios
modelled with female age of first reproduction at 9 showed a faster growth rate (stochastic r greater than 4%)
than the scenarios modelled with female age of first reproduction at 10 (stochastic r lesser than 2%) (Graphs
20 - 22).
Life span and sex ratio
Two parameters were tested for age of senescence - 40 years and 80 years. Populations with longer life span
showed a faster growth rate. Sex ratio of 1:4 with a female bias showed a faster growth rate as compared to
a lower ratio of 1:3. However, population with 1:3 sex ratio retained greater genetic heterozygosity.
Mortalities
Mortality schedules were tried, as in other populations, Higher mortality at 0-1 age class
decreased the growth rate by 2% and the models showed a few extinctions over 100 years.
Female fertility
Female fertility was varied at 92%, 90% and 50%. Lower fertility rates reduced the trend
in growth. Not much of variation was observed between the rates 90% and 92% (Graphs
21 - 26). Populations with 50% fertility had a considerable decline in growth rate and combined with a low
clutch size of 30, the probability of extinction increased
Clutch size
Three clutch sizes of 30, 40 and 60 were modelled. Clutch size of 60 showed a healthy growth compared to
other two. The clutch size of 40 showed a nominal but steady growth rate indicating an optimum size for a
clutch. Populations with a clutch size of 30 showed poor growth rate or when modelled with low fertility
rates, showed a negative growth (Graphs 21 -26).
Catastrophes
The Mahanadi population is prone to various threats such as pollution, fishing, egg collection, floods, effluents,
habitat destructions, etc. which cannot be quantified easily Researchers feel that these threats especially
toxic wastes released in the river causes major damage to the population although they have no way at
present to substantiate their fears. Therefore catastrophe was modelled with a conservative estimate as occuring
once in 10 years (10%) and having a multiplicative effect of either ,55, .75 and .9 on survival
(i.e., survivorship being 55%, 75% and 90% in a population due to catastrophe). The results showed the
population to be able to withstand all of the above catastrophes. The growth rate, however, was affected
(Graph 27).
The Mahanadi population was supposed to be larger a few years ago but has considerably reduced even with
supplementation. This is because of threats due to high pollution, egg collection and fishing.
39
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The Mahanadi population on the whole is more stable in the simulation models than it actually is in the wild.
The results in this model showed no probability of extinction for the population but showed change in
growth rates. Since the model was constructed very conservatively, a very careful look at the scenarios and
the results must be taken.
Obvious depletion in population numbers in the wild has been noticed and it has been attributed to manmade
environmental variations. Since these variations could not be adequately quantified as catastrophes, the
actual scenario was difficult to assess. However, extrapolating with the existing scenarios of the present wild
population and habitat and reading the modelling results on Mahanadi population, recommendations have
been worked out.
Graph 20. Mahanadi population. Stochastic growth rate for
different clutch sizes at 1:3 and 1:4 ratio and ages 80 and 40.
Age of first reproduction for females 9 and for males 13.
40
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Table 9. Mahanadi population.
FILE NAME
DEATH
SEX
CLUT-
RATIO CH
P.B. RESULT
r
(D)
PE%
N
SD
STOCH 'r'
H
TE
r
SD
Female fertility 92%, mortality at 0-1 age class 92%, female AFR 9, Male AFR 13
Maha~003
40
1:3
40
.047
0
440
66.2
90.9
-
.0441
.2160
Maha~004
40
1:4
40
.050
0
436
65.7
88.7
-
.0478
.2202
Maha~005
80
1:4
40
.053
0
438
65.1
88.9
-
.0509
.2198
Maha~006
80
1:3.
40
.050
0
443
63.1
91.2
-
.0497
.2164
Maha~007
40
1:4
60
.074
0
450
62.9
84.6
-
.0713
.2393
Maha~008
80
1:3
60
.076
0
453
60.0
84.1
-
.0728
.2395
Maha~009
40
1:3
60
.070
0
446
63.9
97.7
-
.0668
.2369
Maha~010
80
1:4
60
.084
0
454
59.8
84.7
-
.0815
.2385
Maha~011
40
1:4
30
.034
0
429
67.9
90.9
-
.0321
.2049
Maha~012
40
1:3
30
.030
0
420
64.7
94.3
-
.0290
.2001
Maha~013
80
1:3
30
.033
0
428
60.0
97.2
-
.0312
.2108
Maha~014
80
1:4
30
.039
0
439
63.3
91.4
-
.0367
.2044
Maha~401
40
1:4
40
.040
0
374
100.9
89.8
-
.0362
.3153
Maha~402
40
1:3
40
.037
0
382
110.9
92.2
-
.0331
.3125
Maha~403
40
1:4
30
.025
0
333
136.9
90.2
69.0
.0200
.3000
Maha~404
40
1:3
30
.022
2.0
310
114.9
92.7
55.5
.0169
.2944
Maha~405
40
1:4
40
.039
0
371
107.9
89.8
-
.0333
.3251
Maha~406
40
1:3
40
.036
0
357
116.1
92.1
-
.0298
.3221
Maha~407
40
1:4
30
.024
0
339
130.3
91.0
-
.0200
.3064
Maha~408
40
1:3
30
.021
1.0
309
121.4
91.9
79.0
.0149
.3056
Maha~409
40
1:4
40
.009
4.0
249
143.3
88.7
69.5
.0043
.3354
Maha~410
40
1:3
40
.006
3.0
221
156.7
89.8
66.0
.0011
.3319
Maha~411
40
1:4
30
-.004
11.0
134
124.6
86.5
71.8
-.0100
.3153
Maha~412
40
1:3
30
-.007
8.0
117
95.2
87.5
71.8
-.0106
.3147
41
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Table 10. Mahanadi populations
SEX
FILE
DEATH
NAME
CLUT-
RATI-O CH
CATAS
P.B. RESULT
r (D)
S.
PE
%
M:F
N
STOCH 'r'
SD
H
TE
r
SD
-
.0363
.3190
.0032
.3169
Female fertility 92%, mortality at 0-1 age class 90%, female AFR 10, male AFR 13
Maha~421
80
1:4
40
.75
.044
0
377
104.2
90.5
Maha~422
80
1:3
40
.75
.040
0
366
101.2
92.1
Maha~423
80
1:4
30
.75
.030
0
363
109.3
91.2
-
.0245
.3026
Maha~424
80
1:3
30
.75
.027
0
353
122.1
93.0
-
.0213
.2956
Maha~425
80
1:4
40
.75
.042
0
372
98.2
89.9
-
.0371
.3246
Maha~426
80
1:4
40
.75
.039
0
361
113.9
92.4
-
.0348
.3204
Maha~427
80
1:4
30
.75
.029
1.0
340
122.2
91.0
-
.0223
.33061
Maha~428
80
1:3
30
.75
.026
0
337
117.2
92.8
-
.0214
.3043
Maha~429
80
1:4
40
.75
.016
2.0
284
114.3
91.7
90.50
.0117
.3323
Maha~430
80
1:3
40
.75
.013
3.0
285
137.7
92.2
82.33
.0083
.3277
Maha~431
80
1:4
30
.75
.005
7.0
228
131.2
92.1
68.71
.0009
.3065
Maha~432
80
1:4
30
.75
.002
8.0
198
132.1
91.9
66.50
-.0028
.3124
Maha~051
80
1:4
60
.90
.023
0
369
99.0
89.9
80.22
.0208
.3269
Maha~052
80
1:4
40
.90
.010
4
337
100.0
91.7
-
.0091
.3036
Maha~053
80
1:4
30
.90
.003
8
238
111.6
91.4
68.0
.0009
.2849
Maha~054
40
1:4
60
.90
.010
36.0
287
118.0
85.8
75.25
.0060
.3316
Maha~055
40
1:4
40
.90
-.006
21.4
119
91.7
81.4
70.17
-.0136
.3162
Maha~056
40
1:4
30
.90
-.017
53.4
48
42.0
76.7
72.27
-.0301
.3050
42
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female fertility and different clutch sizes at 1:3 and 1:4 ratio and age 40.
female fertility and different clutch sizes at 1:3 and 1:4 ratio and age 80.
43
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different fertility rates at ages 80 and 40, ratio 1:3 and clutch size 30.
44
Web version
45
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Graph 27. Mahanadi population. Stochastic growth rate at
ages 80 and 40, with .55 and. 75 survival on catastrophe.
Recommendations
1. Studies on the effects of threats must be made in detail. This will help understand the actual role such
threats play on the dynamics of the population.
2. The Mahanadi population has been supplemented continuously over the last 19 years. This has infact
helped the population avoid total extinction. Though continuous supplementations were carried out, the
population has not stabilized. This shows that grave threats are affecting the populations still. Even though
the simulation model showed no extinctions in the populations, high degrees of threats can push this population
to extinction. Supplementation must therefore be carried out.
3. Genetic studies of this population should be carried out to see the difference between the Chambal and
Mahanadi gharials. If the two populations are found not to differ as much as to be classified as distinct
subspecies, supplementation of the Chambal gharials should be taken up in Mahanadhi. This would also
increase heterozygosity in the Mahanadi population.
4. Monitoring and continuous studies of the existing and released gharials must be taken up to study population
dynamics and the effects of pollution on the populations.
46
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CENSUS AND DISTRIBUTION
INTRODUCTION
CENSUS
Conservation and management of gharial necessitates reliable periodic estimation of populations so that
changes may be monitored and management methods modified appropriately. Census of gharial based on
winter day time maximum counts may be done by motor boat to quickly cover metapopulations distributed
over long river stretches. Census on foot is best suited for populations restricted to Small River stretches as
these may be easily repeated for increased accuracy, afford better visibility of animals from elevated observation
sites on river banks and eliminate difficulties confronted during boat census. Methods may be augmented by
night counting with search lights for enhanced accuracy. Surveys to detect occurrence of gharial in new areas
on the other hand may depend on indirect evidence such as spoors at basking sites but require interpretational
skill with regard to spoors especially when such sites are used by large river turtles as well. So different
methods of estimating gharial populations may be used depending on the specific requirements of accuracy
of the estimate. Only a few populations of gharial in India have been censused with any regularity. These are
(i) The Chambal river population censused between the years 1976 to 1978, and again from 1983 to 1985,
then in 1988,1990 and 1994 (ii) the Girwa river population between 1975 to 1976 and again 1988 to 1994
with the exception of 1991 and the population in Ramganga river in Corbett National Park in 1974 and again
in 1994. Other populations/river stretches that have been surveyed at least once are the Mahanadi river in
Orissa; certain rivers of Nepal, Bangladesh and Pakistan, stretches of the Ganga (Rishikesh to Kanpur,
Varanasi to Chhapra and Buxar to Farrakha), the Ghagra river (Kailashpuri to Chhapra) and Protected areas
of the Son and Ken rivers in Madhy a Pradesh.
The results of preliminary surveys indicate a disappointing absence of significant populations, especially
adult breeding groups that are stable and site specific residents, than what would be warranted by the numbers
of captive reared animals that have been supplemented. This suggests that supplemented animals suffer in
either any or all of the following fates
(i)
(ii)
(iii)
Gharial fail to survive outside protected areas
They undergo a high degree of dispersal over very large distance
Survivors are wary and undetectable because of cryptic behaviour.
DISTRIBUTION
The sport value of gharial was never comparable to that of wild ungulates or other large land mammals
and predators such as the rhino and tiger. Consequently, there are few references to the gharial in the better
known works on Indian Shikar. Further, existing references rarely give a complete picture of the historical
distribution of gharial especially with regard to
(i) relative abundance in different parts of its range.
(ii) it’s occurrence in all of the many tributaries which comprise the river systems lying in the species
range and
(iii) the distributional limits in different rivers with increase in altitude or in brackish water habitats in
river estuaries and deltas.
Some very interesting questions exist about the former distribution of the gharial such as those concerning
the species ‘occurrence in the Irrawady river system in Myanmar or recent claims about its occurrence in the
47
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Godavari Systems. Ecological changes of riverine habitat may possibly have irreversibly altered distributional
limits as a consequence of habitat elimination. Research to unearth all available sources of information
especially those not yet known, or accessible with difficulty may fill many gaps in our knowledge about the
species’ historical distribution. Results of recent surveys and census suggest that the present day distribution
of gharial is a small fraction of that in historical times and relatively stable populations are known to be
restricted to some well known protected areas.
The distribution of gharial within one protected area viz. The National Chambal Sanctuary has increased
with the recolonization of at least 9 new nesting sites by 50 + recruits into the population of breeding females.
If this has happened at all or not outside protected areas remains to be revealed by detailed surveys. This is
especially relevant for rivers like the Yamuna downstream of its confluence with the Chambal and the Ghagra
and Gandak in which considerable members of captive reared gharial have been supplemented at upstream
locations creating the possibility of suitable habitat areas by dispersing animals.
48
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REPORT OF THE CENSUS AND DISTRIBUTION GROUP
Group Members: Suresh Chugh, (Facilitator), R.K. Sinha, (Reporter), CM. Vyas, (Recorder), Sudhakar
Kar, R.J. Rao, K.K. Tiwari, S.B. Mishra,, Sandeep Behera, Ishwar Das, A. K. Sinha, B. C. Verma
I. Census
The Working Group first addressed the question of availability of data on distribution of gharial in various
rivers from 1975 to 1994 as well as what is the current status of gharial. The group also attempted to evaluate
whether the efforts till date were sufficient.
It emerged that some of the areas have been covered fairly regularly such as Katerniaghat and Chambal river,
but others have not been surveyed for some time. It emerged that there was a lack of consistency in timing of
survey, survey strategy, etc. which was felt by some of the researchers to be a problem. Also, the researchers
and field officers felt that a lack of coordination among the participating state agencies in census operation
for multistate habitats was a matter of great concern.
It was noted during discussion that in Orissa more sightings of young and subadults of less than 6 ft. length
were reported during night surveys/census and gharials of larger size were sighted more during the day time.
II. Distribution:
A detailed map of historical and present distribution map is needed to monitor and rehabilitate the gharial in
future.
The working group felt that it would be useful to pinpoint more precisely whether and to what extent the
distribution range had altered.
The Group also considered if releases had been made in suitable areas with regard to the distribution of the
species and impact this has had on pre-project distribution.
It emerged that sufficient data on current distribution was not available. However, whatever data was available
was listed to form baseline information. The Census and Distribution Chart # I lists this information including
historical, pre-Project figures and present distribution. In view of the lack of monitoring for some areas, data
was divided into categories and a “Data Quality Index” utilised. The Categories in the Data Quality Index
are 1. Census - where figures reflect actual monitoring results; 2. Scientific Estimate, - where figures are not
from actual monitoring but have been given on the basis of some available scientific information; 3. Anecdotal
- where occasional, anecdotal information was contributed. As apparent from the Chart, there is a need for
monitoring figures for many of the areas.
Recommendations
I. Census
As, a comprehensive census of gharial is manpower intensive, it is recommended that the local universities
and college students as well as NGO’s, Panchayat, and other village based bodies/individuals should be
motivated and involved to participate in Gharial census activity in addition to wildlife personnel and
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researchers. A methodology to encourage them, such as that used by BNHS in their bird survey, may be
considered.
A briefing session should be organised for all the participants, especially volunteers and persons not experienced
in census work, before census every time. In view of the lack of agreement on methods of information
gathering for Gharial, a brief brochure dealing with census techniques should be prepared and made available
to all the agencies associated with the census.
It was felt by some of the members of the Working Group that motor boats should be avoided as far as
possible while doing census as these may disturb the animals. Sailboats or oar boats could be used.
The Working Group felt that it is very important that annual census should be conducted. Field maps indicating
preferred basking sites should be prepared during every census exercise.
Noting the lack of coordination between range states having Gharial, the Working Group felt that the
participating state agencies should be coordinated. A Central Coordinating Unit for Gharial is proposed as a
mechanism for providing coordination in an efficient and effective manner.
The Working Group strongly recommended that baseline data should always be collected before new animals
are released and information should be shared among range states.
The Working Group recommends that census should be done for the whole stretch of river and not merely in
the “identified habitats”. *
The Working Group recommends that census should be done simultaneously in all range states, for which
one month in winter should be fixed in which the maximum number of sightings are possible.**
As there are a number of agencies conducting surveys, it would be a valuable exercise to collect and collate
the experiences of the agencies doing Gharial monitoring and census and a workshop held with the objective
of standardising census methodology. It was pointed out by some members of the Workshop, however, that
differences in individual areas exist which would require a somewhat different strategy. This could be included
as Notes or Appendix in the document produced by this exercise.
II. Distribution
A detailed historical distribution map should be constructed from published information available in Boulenger,
Smith, Hodgeson, BNHS Journals, District Gazetteers of the range states, and other historical references.
Even ancient literature such as Ainee Akbari, Akbar-nama, etc. can be consulted for this map. Old royal
family shikar records should be researched for this purpose, as well.
A distribution map giving status of species before 1975 when the Gharial Project started should be prepared
and made available to concerned authorities.
A current distribution map should be constructed based on the information gathered from the different states
on the present day status of the species. This should be updated year by year as census is completed and new
figures and information becomes available.
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The Wildlife Departments of the range states can take up a survey exercise to establish the current range of
distribution of gharial in the instance that the comprehensive census proposed earlier does not take place.
Information — anecdotal or about occasional sightings with the help of fishermen in particular, local schools,
colleges, universities, and village bodies should be collected for a better understanding of the current
distribution of the species.
Dissenting comments:
* Note: Mr. Basu felt that this was not a useful recommendation and that detailed census
(as apart from surveys) should be done in identified habitats so as to save time and resources.
** Note: Mr. Basu (and a few others) felt that this may be impractical due to the different
conditions in the various range areas.
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CENSUS AND DISTRIBUTION GROUP: CHART 1
AREA
STATUS /
POPULATION/
HISTORY
PRE-GHARIAL
PROJECT
RIVER
RELEASES
POST-RELEASE MONIT
PRESENT STATUS / POPULATION NUMBER
Data Quality Index
CENSUS
NEPAL
KOSI(SAPTKOSI)
BIHAR
-DO-
NEPAL
-
NEPAL-84
-
-
RELICT IF ANY
"
<12*
-
NIL
-
-
-
NARAYANI
-KALI GANDKI
"
(30-40)+ NEPAL 175
NARAYANI
SURVEYED
N.A.
-
-
BIHAR
GANDAK
"
<150
-
-
-
TOTAL <100 -
SON
"
-
-
-
BIHAR
GANGA
"
<10°
-
INFORMATION
COLLECTED DURING
DOLPHIN SURVEYS
-
3-4 BR.GROUPS
RUM ORED TO
SURVIVE
-
BIHAR
-
-
NEPAL
KARNALI
"
35(20)+
-
GIRWA CENSUSED
50-60 +
-.
U.P.
GIRWA
"
14(06)
399
1975-79,88-94
GHAGRA
"
<10*
291
KARNALI SURVEYED NA
NEPAL
U.P.
RAPTI
"
-
5
10
NEPAL SURVEYED
NIL
-
<15
-
-
U.P.
GANGA
"
<15°
225
PRELIM.SURV OF
PORTION IN 1992
-
<15
-
RAMGANGA
"
<5(4)+
257
CENSUS 1994 49(8)
-
-
-
SARDA
"
-
260
SURVEYED ALONG
WITH DOLPHIN
-
-
-
YAMUNA
"
-
-
-
-
-
-
<10
SURVEYED
IN 1994
-
"
105
CA. 35
SON
KEN
"
?
35((MP)
?
?
-
-
TONS
"
-
-
-
-
-
-
BETWA
"
-
55(UP)
-
-
-
-
CHANDRAPRABH
A
"
-
-
-
-
-
-
"
<15 0
30
BABAI IN NEPAL
SURVEYED IN 1989
CENSUS
(7)+
-
-
U.P.
U.P.
M.P.
COMM
ON*
-
ESTIMATE
ANECDOTAL
PRELIM. SUR. OF
GHAGRA
POPULATION
M AY SURVIVE
UPSTREAM OF
RELICT IF ANY
IN 1992 = <100
SURVIVES<50
MP/UP
UP
NEPAL
BABAI
UP/MP
CHAMBAL
""
107(32)+ Ca. 1800
1976-78
NOTE: 1. GOOD EVIDENCE EXISTS OF ABUNDANCE OF GHARIAL THROUGHOUT ITS HISTORICAL DISTRIBUTION
WITH EXCEPTION OF MARGINAL HABITATS
2. FIGURES IN PARENTHESES REPRESENT ADULTS* BASED ON LITERATURE;
O
CONJECTUR/ESTIMATE/SC. GUESS J+SURVEY AND CENSUS ESTIMATES
NA. FIGURES NOT AVAILABLE.
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HABITAT
Introduction
Essentially rivers are the habitat of gharial. Other than rare records of juveniles and sub-adults living in
inland water bodies such as lakes and ponds, gharial have never been found outside major rivers. In
literature its habitat often has been described as “deep and fast flowing rivers”, but in fact gharial select
semi-stagnant aquatic habitats which exist in the pools of deeper waters within rivers. In these, gharial
have to expend lesser energy against currents of flowing water to avoid dispersal beyond their preferred
home range. Even young gharial less than 2 m in length which are found in swifter flowing river stretches
occupy relatively semi-stagnant micro-habitats. Curiously gharial avoid the lake-like habitats of reservoirs
above dams and barrages where there is no perceptible current.
Before descending to an elevation of 300 m. MSL rivers are too rapid and rocky to be normally suitable for
habitation by gharial and gharial may also not have been common in brackish water environments of estuaries
and deltas especially in those dominated by the estuarine crocodile.
With the exception of adult males in the breeding season gharials are social animals, They are also
moderate feeders like all other poikilothermic crocodilians occurred in high densities in the past, in most
parts of its range. The major limiting factors which restricted population densities were, apart from the
territoriality of the males, overcrowding at the terrestrial components of habitat such as communal basking
and nesting sites.
So far the carrying capacities of different gharial habitats have never been scientifically assessed.
However, on the basis of existing literature, and their occurrence densities in certain areas even today
ideal river habitat can easily support probably as many as 10 - 20 adults per kilometer.
Habitats and/or their carrying capacities have shrunk in recent times because of a number of man-induced
ecological changes or the increase in human activity or habitation on river banks. Acute and irreversible
changes have been caused by irrigation and hydroelectric works. Irrigation projects exist on nearly all
range rivers with the exception of the rivers of the Bramhaputra system. Sometimes in rivers such as the
Ganga and Sarda water is abstracted for irrigation systems by a series of barrages and lift irrigation
schemes. Water abstraction reduce natural discharge of rivers and consequently stream width and depth.
These may also create unnatural hydro-mechanical regimes disrupting natural activity cycles of both
gharial and fish. Migration and breeding of fish, the exclusive prey base of gharial, are also obstructed by
the presence of dams and barrages.
River fish themselves may be threatened not only because of the disruptive influence of dams and
barrages but also from intense and indiscriminate artisanal fishing practices. Watershed degradation have
resulted in serious floods and intensified erosion of river banks and have contributed to detrimental
modifications of the hydrological characteristics of the rivers.
Because of intense persecution and killing of gharial in the past, wild gharial perceive threat in the human
form and will desert otherwise suitable habitat in close proximity of human habitation and activity.
However, captive reared gharial after release in rivers show much reduced threat responses and flight
distances to human beings. So if left unpersecuted, especially if not injured or killed when accidentally
netted, mere human presence by itself may not be a limiting factor in gharial habitat.
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REPORT OF THE HABITAT WORKING GROUP
Members: Manoj Mishra, (Facilitator) D. Basu, (Recorder and Reporter); B.C. Choudhury, R.C.
Gupta, S.M. Hasan, M.R. Yadav, J. N. Saxena, R. K. Pandit, IshwarDasf B. K. Sahu
1.
OBJECTIVES
The group took as their primary objectives to
1.1 Define the “ideal” habitat characteristics
1.2 Make (preliminary) estimates of carrying capacity of existing habitats
2.
METHODOLOGY
The Group adopted the following methodology for achieving objectives.
2.1. The Working Group first examined the attributes of habitats where gharial occur
naturally at present (identify qualifiers).
2.2. Secondly, in determination of gharial habitats, an approach has been adopted
whereby the essential requirements for the gharial with regard to its biology were
analysed. Since the gharial is an inhabitant of rivers, the first step was to identify those
rivers which have been historically inhabited by gharial. It was also attempted along with,
to list such rivers which though possessing seemingly suitable gharial habitat were not
known to have contained gharial. (See Habitat Chart I)
2.3. Thirdly, on a higher level of classification of qualifiers, habitat was considered to be
composed of both i) aquatic and if) terrestrial components. The characteristics of each
different size classes of animals were catalogued.
2.3.1 Aquatic habitat components
A catalogue of characteristics of aquatic components is listed as follows:
(a)
Perenniality of the stream
(b)
i. Adults: Free flowing but deep semi-stagnant pools;
ii. Juveniles: Existence of comparatively semi-stagnant eddies in river stretches
which are shallower and swifter flowing in comparison to habitat inhabited by
adults.
(c)
(iv)
Existance of perennial or seasonal side channels within annual
home range for flood evasion behaviour.
Special characteristics of river bed for courtship/mating.
Shallow water beds contiguous with deep pools within the flowing river
streams.
v)
Minimum stream width : ca 100 m
vi)
Other attributes: unpolluted and preferably devoid of any human habitation
2. 3.2 Prey availability is, of course, a determining characteristic for suitability of habitat. The
following characteristics of prey, e.g. fish, were listed.
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i)
ii)
iii)
2.4
Prey item: Scaly and non scaly fish
Prey size: ca. snout length of gharial
Prey density: As predators gharial are efficient enough to
capture prey in areas where fish populations may be depleted, but the existence of a
critical lower threshold of fish population density has to be assessed,
Terrestrial component This can be further classified on the basis of the two territorial activities
of gharial;
i) basking and
ii) nesting
Gharial show strong preference for river stretches with sandy banks although they have been found
to adapt to clay/mud banks in obligatory situations.
2.4.1 Basking sites
Adults - Mid-river sand bars or reasonably flat and smooth rock promontories (that are exposed but
not higher than 30 cms above water surface or just submerged). Basking sites must adjoin adult
aquatic habitat described earlier.
Sub-adults and juveniles: similar as for adults and preferably adjoining the earlier described
aquatic habitat of these size classes
2.4.2 Nesting sites
i) Steep sandbanks: 2-3 ms high above water level in snow fed tributaries and at least 1 m
high in southern tributaries.
ii) Depth of sandy layer should be greater for larger females and in excess of minimum
depth (45-60 cm) for smaller females
3.
Availability of Habitat ~ Recommendations for Assessment
3.1. Availability/Status of Habitat should be assessed on basis of fulfillment of
above described prerequisites by surveys of listed rivers.
3.2. An adequate numbers of surveyors selected for this work should be trained in survey
competence-through special workshops.
3.3. Food preference needs to be investigated using state of art techniques before work on actual
prey availability can be assessed in the field.
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THREATS
Introduction
By the end of 1960’s the gharial had dwindled to a trace of its former abundance due to combined effect of
shooting, hunting for skin and meat, and loss of habitat from river alteration and human settlements. Under
the Wildlife (Protection) Act, 1972, the species was protected by declaring it as an endangered species. The
international laws have equally protected the species by including the gharial in Appendix I of CITES and in
the IUCN Red-data Book. Although the animal is well protected legally, the increasing human pressure on
gharial habitats as well as other threats bode ill for the long term survival of the species.
The various factors which have threatened the survival of gharial as a species have changed with the passage
of time. These changes have been quantitative as well as qualitative. The degree of threat represented by
some of these factors, such as killing for skins, has altered over time. While none of the factors responsible
for rapid decimation of population in the past have disappeared entirely, even new sources of threat have
originated. These are mostly from man induced ecological changes which affect either the species itself or its
prey base.
Although this has not been extensively documented the indiscriminate killing of gharial either directly for
skins or accidentally in modern fishing gear such as nylon set gill nets, has been largely responsible for the
extermination of the species from extensive river stretches that were formerly described as ‘abounding’ with
these animals. The regulation of international trade in crocodilian skins by enforcement of the CITES
agreement, as well as then organised production from several international source areas, has reduced the
profitability of poaching crocodiles or gharials to the extent that their skins no more constitute a significant
proportion of clandestine consignments of wild animal products that are detected in India from time to time.
Although deliberate killing of gharial for hides may have ceased to a large extent, accidental killing resulting
from intensified artisanal fishing with modern nylon fishing gear continues to exist and may constitute one
of the main hurdles in the success of supplementation/reintroduction programs.
In the near and distant future the main threat to the survival of self-sustaining populations of gharial arises
from the intense competition they will face from man for the three resources which occur in their habitat, viz.
fish, water and riparian lands. A major proportion of the species range lies within the Indo-gangetic Plains
which are reputedly some of the most populous regions in the entire world. This competition may intensify
with unchecked growth of human populations. Threats to the species should not be assessed in isolation —
they are very similar to those threatening a collapse of the great river eco-systems of this region, and a
concomitant loss of their biodiversity. Successful biological conservation implies that man will have to
ascribe an appreciable value to the health and biodiversity of these ecosystems irrespective of whether this
value is an economic, ecological, scientific, cultural or aesthetic one. The Report of the Threats Group is as
follows:
56
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REPORT OF THE THREATS WORKING GROUP :
Group Members: Brij Bhushan Sharma, Facilitator; B.C. Choudhury, Reporter; Dr. Dalwani; Dr. B.A,
Daniel, Recorder; Ms. Fahmida Hanfee
In India the Gharial population exists in the four major River systems, e.g.
a) Mahanadi; b) Southern tributaries; c) Main Ganga; d) Northern tributaries
All these river systems have a varied degree of threats (direct and indirect) affecting the survival of
gharial populations. The Working Group listed the direct threats as:
1
Removal of eggs
2.
Poaching of animal for medicinal use
3.
Incidental catching in fishing nets
4.
Accidental killing
5.
Bamboo rafting.
6.
Dynamite fishing
7.
Inbreeding
8.
Subsidised predation
9.
Trade
10.
Small Population size itself
and indirect threats as
1.
2.
3.
4.
5.
6.
7.
Construction of dams
Pollution
Riparian cultivation
Man induced floods
Intra-specific conflict
Public attitude/practices
Sub-optimal captive management practices
See Chart 1.
The Threats Working Group addressed the following objectives:
1)
Riverwise categorisation of the threats. The rivers were listed under Southern Tributaries as
Chambal, Ken, Son; Mahanadi, Main Ganges, and Northern Tributaries Girwa, Ramganga, Brahmaputra
and Ghagra and Sarda. See. Chart 1.
2)
3)
Degree of threats
Frequency of threats
These were listed on a scale of 1Least 2 3 4 5 6 7Highest and rated in Chart # 2.
On the basis of this listing and rating scale, the Threats Group has formulated the following
Recommendations:
1) Systematic monitoring of the river systems to assess the present status of gharial after supplementation
is an urgent requirement.
57
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2) A systematic, coordinated and concentrated research programme is needed to determine the degree of
impact of several threats and of the conservation measures taken in the last twenty years.
3) Education and awareness at community level is required to provide a defense against various manmade threats,
4) Rivers (like Mahanadi) with high frequency of threats should be taken up for special study and
monitoring on priority basis.
5) Genetic studies should be done so that it can be determined whether or not inbreeding constitutes a
genuine threat to the various populations of gharial.
(The computer modelling exercise indicated that a lack of heterozygosity resulting from inbreeding may be
a problem in some populations. Also very little is known, about the age structure of the populations. As no
genetic management has been considered in release programmes to date, it is strongly recommended that
managers take cognizance of genetic and demographic factors when planning further release.)
6) Coordination with the Irrigation Deptt of the respective states to determine the likelihood of flooding
and avoidable man-induced floods.
7) Control measures for unprotected areas having gharial populations. Identify community nesting areas and
provide protection to the nests to reduce the risk of predation.
As there are many Gharial in unprotected areas, threats such as fishing, sand mining, river bed cultivation
and industrial pollution can be controlled best by education/awareness activities.
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59
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Incidental catching
in fishing nets
Accidental killing
Bamboo rafting
Dynamite fishing
Inbreeding
Subsidised predation
Trade
3.
4.
5.
6.
7.
8.
9.
yes
no
Man induced floods
Intra-specific conflict
Public attitude/practices
Captive management
pract ices
4.
5.
6.
7.
yes
no
no
Riparian cultivation
3.
no
no
Pollution
Construction of dams
INDIRECT THREATS
yes
no
?
no
no
no
no
yes
no
yes
Mahanadi River
2.
1.
Small Population
size itself
Medicinal use
2.
10.
Removing eggs
1
DIRECT THREATS
River
System
= no population
no
no
yes
yes
yes
no
yes
no
no
yes
?
no
no
no
yes
no
no
Chambal
no
yes
no
no
no
no
no
yes
no
no
yes
no
no
no
no
no
no
Ken
no
no
no
no
yes
no
yes
yes
no
no
no
yes
no
no
yes
no
no
Son
Southern Tributaries
Gharial PHVA -- Threat Matrix
no
no
no
no
yes
yes
yes
yes
yes
-
yes
no
no
no
yes
no
no
Main Ganges
no
yes
no
no
no
no
yes
yes
yes
no
no
no
no
yes
yes
no
no
Gandak
yes
yes
no
yes
yes
yes
no
no
no
no
no
no
no
no
no
no
yes
Girwa Ghagra Sarda
Northern Tributaries
no
no
yes
no
no
no
no
no
no
no
no
no
no
no
no
no
yes
no
yes
yes
no
Brahmaputra
no
no
no
yes
no
no
no
no
no
no
no
no
Ramganga
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1
1
6
2
KEN
SON
MAHANADI
MAIN GANGES
1
1
RAMGANGA
BRAHMAPUTRA
GHAGRA & SARDA
6
GIRWA
NORTHERN TRIBUTARIES
1
CHAMBAL
5
1
1
6
6
6
1
6
IC
5
1
1
2
2
2
1
3
AK
4
BR
1
1
1
2
1
1
1
NO POPULATIONS
5
1
2
1
1
1
1
1
MU
SOUTHERN TRIBUTARIES
RE
2
1
5
1
2
1
1
2
DF
NO
NO
NO
YES
NO
NO
YES
YES
IB
DIRECT
Gharial PHVA - Threat Ratings
1
1
2
5
2
2
1
5
SP
2
1
2
5
2
2
1
2
1
6
2
6
6
6
5
1
TRE SPS
1
2
1
6
2
5
1
5
CD
1
1
5
5
2
2
2
2
PN
1
1
2
5
2
6
2
6
RC
2
2
2
1
5
2
1
5
MF
INDIRECT
2
1
2
2
5
2
1
5
IC
5
1
5
3
5
2
4
1
PA
2
2
2
6
2
4
2
5
HA
1 ---
1
1
1
2
1
1
2
WCM
TRADE
Introduction
The Crocodilian species have attractive and durable hides which make them desirable for the leather trade.
In some countries, the wildlife establishment has attempted to amalgamate conservation and consumption
of wildlife products in a sustainable manner with varying degrees of success. There is a general feeling
among global conservation seers and policy makers that sustainable development of natural resources is
the key to the salvation of species and their habitats. A policy statement on sustainable use has been
drafted and is in the process of revision. A special task force has been set up for this purpose.
Two decades ago, when the crocodile project first started, there was an idea that farming of mugger
crocodiles might be a viable proposition. Afterwards, the Government of India took a decision not to
allow farming of wild animals for commercial purpose.
There were specific requests to address the subject of Trade by the I.G., Wildlife, and Ministry of
Environment as a personal remark to the facilitators and in a letter to the organisers by the Chairman of
the Crocodile Specialist Group, SSC, and IUCN. Because there have been repeated requests to open trade
for crocodilians in India, the Trade Working Group was created at the P.H.V.A. to examine the feasible
from a biological, economic, and ecological as well as cultural point of view and give an opinion by the
P.H. V. A. Workshop,
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REPORT OF THE TRADE GROUP
Members: Ms. FahmidaHanfee, Faciliator; BrijBushan Sharma, Recorder, Reporter; Bipul
Chakraborty; Ravikant Pandit; Suresh Chugh; B. Dutta Gupta; D, Basu
Introduction
It is believed that due to commercial value of the skin, for preparing various leather goods, the
populations of gharial were largely hunted. In addition to the trade in skins, crocodile eggs, meat, fat, gall
bladder and other parts makes it worthwhile to kill crocodiles. The 1964-65 statistics show the export of
Rs. 24,000 worth of crocodile skins to U.K. and France. However, with the ban on crocodile killing during
1975, the skin market went underground. There are very few official records of gharial trade. With the
belief of growth of gharial population, especially in captive conditions, a question has been raised both by
national and international organisations concerned with crocodiles to allow sustainable utilisation of
gharial for commerical purpose through crocodile farming.
The conclusions drawn from the discussions and opinions of the Trade Working Group indicate that there
are no official reports of gharial trade in India. As far as illegal trade is concerned, scanty reports are
available, one of live Gharials being sold at Patna market and other of Amsterdam where the gharials are
being sold at a price of $300 per gharial. It is also known that gharial is sometimes locally used for its
eggs, meat and medicinal properties, which constitutes a sort of small scale commerce.
Recognising that the international conservation community strongly supports, and even encourages, the
concept of trade in animal products when it can be done sustainably and also that there is interest in
establishing commercial farms for crocodilians in India from different agencies, the Trade Working Group
has discussed the merits and demerits of commercial farming and opening of trade in the Indian context.
We have concluded that it is not in the best interests of the conservation of wildlife in India to opt for
trade of this species.
1. Cultural values: The basic ethics of the country towards wildlife conservation and animal life cannot
be ignored. Indians do not look at animals merely as a source of meat, hide and horns. From ancient times,
animals — including both wild and domestic species — have been protected by imperial edict and
religious principle. While it may not possible or even desirable to convert everybody into a vegetarian, the
basic approach of the country is not to deny to right to live, to all living beings. It is even part of the
national Constitution, e.g. Article 51 A.
Killing of animals for monetary benefits is discouraged by a large number of people in India. People have
religious sentiments attached with their lifestyles. This must be respected.
2. Protection and legal aspects
Gharial is included under Schedule I of the Wildlife (Protection) Act, 1972. It is classified under
Appendix I of CITES, as Endangered in the Red Data Book of IUCN and also the Red Data book of
Indian animals by Zoological Survey of India.
Accordingly, any commercial dealing in such species is strictly prohibited. It would require that the
Wildlife Act of the country be modified in order to bring trade into operation. Having altered the law for
one order of animals, it is a short step to changing the law for others. It would open a floodgate of requests
for alterations to the Act.
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3. Wrong signals about conservation. If the Government of India should take up commercial farming, the
general impression will be created in the villages as well as urban areas that the Government has relaxed
the legal provisions regarding ban on killing, so poaching of animals is likely to increase.
4. Increasing illegal trade. With the poverty that exists in the country, particularly amongst the fishing
community, it would be very difficult to exercise any effective control over capture of animals from the
wild. These wild caught animals could be laundered very easily for the purposes of exploitation in the
garb of captive bred animals. Commercial farming and trade is likely to lead to an increase of lust of the
urban elite and rich people in the foreign countries to use wild animal’s skins for consumer items which
will encourage their demand in open markets.
5. Illiteracy of the poor people. Many of the people of India are illiterate and unsophisticated and unable to
distinguish between sustainability and exploitation and the consequences of the latter.
6. Some of the Working Group of the PH VA have concluded that while the Gharial population can be
sustained in the wild by supplementation, it cannot be easily increased to large numbers. Therefore the
animal is likely to stay on the endangered list in perpetuity.
Recommendations:
1. The Trade Group recommends a survey to assess the dependency of people on fisheries in and around
the protected areas. (Partial or total dependence)
2. Categorisation of the people.
3. The requests which have come from within India for opening up of trade in crocodilian products in
recent years stems in part from the surplus animals which exist with different agencies which bred them in
anticipation of need. Zoos and rearing centres should therefore be mindful to rear only such numbers of
Gharial as are required by the authorities responsible for supplementation. In the case of accidental
surplus accumulated “in good faith” and not required for conservation due to unavoidable circumstances,
the Government of India will undertake to support the animals for the rest of their natural lives.
5. The Working Group recommends that Education Programmes focusing on Gharial should include as a
target group the local people in and around gharial habitats who might be using Gharial for non-tannery
products.
6. It is recommended that enforcement officers (customs, local police and the forest department) be
trained in identification of seized animals and their products.
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REINTRODUCTION
Introduction
Under the Crocodile Project, which was initiated by the technical expertise of Dr. H. R. Bustard, several
State Governments have established crocodile breeding and management programmes. To reduce natural
losses through management, the ‘grow and release’ technique was adopted, which involves incubation of
wild-laid eggs in artificial hatcheries, rearing of young in controlled environment and releasing of grownup
(over a meter length) animals in protected areas. So far around 3,865 captive, raised gharials have been
released in 12 rivers in the country. The post-release monitoring indicated that the habitats have accepted the
released animals and there are increasing trends in the populations. It is felt that in the near future, as the
recruitment into the adult group steadily increases, new areas may have to be developed to attract sub-adults
to settle to form breeding groups. In addition, new releasing sites have to be identified for reintroduction of
gharial.
The recent instructions of Govt, of India to different State Governments regarding closure of egg collection
by the rehabilitation centres became a great concern to many scientists and managers. In the Gharial PHVA
workshop a working group for Re-introductions has been formed to discuss the future strategies for gharial
re-introduction. The group consulted the draft-guidelines for reintroduction proposed by the IUCN/SSC/
Reintroduction Specialist Group.
Captive reared gharial have been both reintroduced in areas where they had been extirpated locally and also
used for supplementation of relict populations. The major proportion of captive reared stock was produced
through the collection and incubation of eggs laid by wild gharials, but eggs produced in captive breeding
facilities have also contributed to this in recent years. Production of captive reared gharial for supplementation
began with the inception of the Government of India gharial project in 1975-76 and since then continued
without respite till 1992. During this period approximately five to six hundred eggs were collected from the
nests of wild gharial every year. The overall production of animals for supplementation amounted to 40% of
eggs collected. This represented an 8 to 10 fold increase in the survival of young gharial from eggs laid in the
wild and, therefore, justified the supplementation programme of relict populations. Supplemented gharial
were “head started” before their release in the wild by rearing in captivity for varying lengths of time. To date
no studies have conclusively established any advantage accruing from a “correct” supplementation
methodology with respect to age/size of animals at release, selection of release sites or season. Generally
accepted thumb rules are; a minimum size of 1.2 metres length; the upper most stream point with a protected
area preferably those inhabitated by animals of similar size; release should be completed earliest following
the final recession of monsoon river spate and animals should not be released directly into flowing water but
on land.
In practice there have been many deviations from the above rules as well as from IUCN guidelines for
reintroduction. From a total of ca. 4000 captive reared animals which have been released in rivers, 60 to 65%
have been used for supplementation of relict population within protected areas, which 35% were reintroduced
in unprotected areas within the species’ former distribution but where they did not occur anymore.
The supplementation exercise has been most successful in the Chambal river where approximately 33 per
cent of the animals upto age 5 were recorded to have survived within the protected National Chambal
Sanctuary, For animals of age 5 to 9 the recruitment rate rose to 79%. It is note worthy that after age 9;
gharials show a marked tendency to become residents of a preferred home range. Plausible reasons which
have contributed to comparatively rapid population recoveries of the gharial in this river are;
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(i) Ideal habitat conditions (See Section habitat),
(ii) Abundant prey base,
(iii) Minimal disturbance because of remote and’ inaccessible locations,
(iv) Management inputs such as total fishing ban and surveillance by sanctuary staff.
Similiar conditions also prevail in the Girwariver within the Katerniaghat Sanctuary, but
recruitment into this population has been now here comparable with that of the Chambal river.
The most conspicuous differences between conditions prevailing in Chambal and Girwa are:
(l) the miniscule extent of habitat in the Girwa (8to 10km) in comparison to the 400 kms of protected
habitat of the Chambal river.
(ii) The disruptive presence of an irrigation barrage located within 10 km of the downstream boundary of
the Katerniaghat Sanctuary. As a result, an unknown percentage of gharial are lost from the sanctuary
population where (a) they enter irrigation canals and are unable to return to the main river, (b) they disperse
along the river, downstream of the barrage, but cannot migrate into the sanctuary area because of the
surmountable barrier presented by the barrage, (c) animals die in accidents at the barrage gates.
The most significant reason for the higher success rate of the supplementation programme for the Chambal
river population would, however appear to be the extensive protected river length available to the released
gharials.
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REINTRODUCTION WORKING GROUP
Members: R. J. Rao, Facilitator; D. Basu, Recorder/Reporter; Manoj Mishra; S. M. Hasan;
Dr. D. N. Saxena; Dr. L. N. Acharjyo
POLICY RECOMMENDATIONS
The Workshop recognized that the supplementation activities under “Grow and Release” programme
taken up in the last two decades have been successful in increasing the population. The modelling
exercise clearly showed that without these supplementation activities the probability that these
populations would have survived was very, very low. This conclusion is borne out by the fact that
supplementation of the Chambal population with nearly 1788 animals, plus an estimated natural nativity
of 1165 animals (a total of 2953 animals) has resulted in the recruitment of only 300 adults and subadults.
This represents an actual population increase of 17% in 16 years, or only 1% annual growth rate.
The Working Group has listed the rivers belonging to Ganges and Mahanadi river system in which
successful gharial grow and release (supplementation) efforts have been made, e.g. Chambal, Son, Ken,
Girwa, Ramganga, Mahanadi. It is felt that supplementation in all the above rivers should be continued.
As already recommended by the habitat sub-group, extensive surveys by trained personnel should be
carried out in the states of U. P., M. P., Orissa, Bihar, West Bengal and Assam to determine suitable habitat
for possible further re-introductions. The Reintroduction Working Group noted the insufficiency of
information about the areas where the species occurring earlier and became extinct. A committee of
experts may then decide on the basis of survey results regarding the most appropriate site for actual
reintroduction sites. Reintroduction of animals in Brahmaputra River should be taken up on priority
because no previous conservation measures have been taken for the species there.
A strong and continuous monitoring component should be built into further supplementation /
reintroduction programmes.
Requests for reintroduction of gharial in the historical range of Pakistan, Bangaladesh, Nepal, Bhutan, and
Burma should be encouraged and surplus Gharial may be donated to those wildlife establishments for
conservation purpose.
The Working Group recommends that re-introduction/supplementation programme should be as per the
guidelines of the IUCN/SSC re-introduction specialist group with necessary modifications locally.
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Technical recommendations
1. Releases for supplementation are made at a standard optimum size. It is now known through experience
that smaller sized animals are highly dispersible so it may be beneficial to release a smaller number of
larger animals with a cost equivalent to a larger numbers of smaller animals.
2. Rearing procedures such as hand feeding should be discouraged to eliminate the possibility of human
familiarity which will increase vulnerability of animals when released in the wild.
3. Release procedures require to incorporate orientation of animals to be released in flowing water habitat
by a minimum period of rearing in such enclosures where flowing water habitat is simulated.
4. Releases must strictly adhere to accepted norms of relate season post- monsoon - to pre-winter and
release in habitat (in vicinity of wildly occurring similar sized animals until the norms have been
scientifically demonstrated to be suboptimal in effectiveness
5. Release procedures have to be standardised for optimal efficiency, e.g., state-of-the-art techniques such
as radio telemetry to monitor fate of individual batches of releases as against general monitoring that have
been recommended elsewhere.
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PROSPECT OF FURTHER GHARIAL REINTRODUCTION
IN RANGE STATES IN INDIA *
INP.A.'S
OUTSIDE P. A.'S
U. P.
Yes
Yes
M. P.
Yes
No
Bihar
Yes
No
Orissa
Yes
Yes
West Bengal
Yes
?
North. East
Assam
?
.
COMMENTS
Need to survey
PROSPECT OF FURTHER GHARIAL REINTRODUCTION IN RANGE
COUNTRIES IN INDIAN SUBCONTINENT
Stocks to come from:
INDIA
Y
INDIA
NEPAL
Y
INDIA/NEPAL
BANGALADESH
Y
INDIA
PAKISTAN
?
INDIA
BURMA
?
NEPAL
BHUTAN
?
?
* CHARTS GENERATED BY B.C. CHOUDHURY ON BASIS ON INPUT FROM
STATES REPORTING SESSION
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-
Rapti
Ghagra
Swarda
Mahanadi
Chambal
National
600
30
45
07
Ganga
Ken
-
Betwa
209
50?
Ramganga
Son
13
3
Length of
river
protected
(km.)
Girwa
2
Rive
r
Orissa
M.P.
U.P.
1
State
1788
609
50
17
35 - 45
young
260
291
10
245
55
257
399
4
Number
s
released
adults and sub
adults 250-300
young 850900
25-30
10-15
adults < 5
*
*
*
*
6 adults and sub
adults
*
-20 A.D.
5
Proportion
successfully
recruited into
population
250 adults
500 sub adults
adults 80-100
<25
100
6
Estimation of carrying
capacity of Protected
habitat
3500
3500
500-1000
2000
7
Necessity of
sustained release
100
35
20
20
8
Number
of years
REINTRODUCTION GROUP -- CHART I
100
100
50
100
9
Annual
Release rate
CAPTIVE POPULATION
Introduction
Reviews of captive breeding of crocodilians point to its feasibility in the case of most species. Significantly
however, so far only three establishments in the world, viz. Kukrail Rearing Centre, Madras Crocodile Bank and
Nandankanan Biological Park have achieved regular success in breeding the gharial in captivity, although at least
15 known establishments hold adult males and females. Five of these are within India, and the others elsewhere in
the world.
Likely reasons for the failure to breed gharial on the part of so many institutions may most easily be discovered by
examining the comparable attributes of the establishments where it has been successful. These may be catalogued
as under:
1.
2.
3.
4.
5.
Location within the natural distribution of the species
Spacious enclosures especially planned for their breeding
Adequate seclusion and privacy in the breeding enclosure
Planned acquisition of adequate compatible breeding stock.
Availability of species expertise
The last two attributes are perhaps the most difficult to acquire, at least at short notice. This is because of the late
attainment of sexual maturity in the species (12-15 years in ideal conditions) and requisite species expertise comes
only from protracted and first hand, both in situ and ex situ experience. So at establishments intending to specialize
in captive breeding of gharial, both breeding stock and expertise need to be maintained as a tradition and that too
with continuity. This emphasizes the need for planned and coordinated long-term approach to ex situ metapopulation management, if zoos and other ex situ breeding facilities are to actively contribute to supplementation
programmes for in situ conservation. Well-managed ex situ facilities are also useful in a number of exclusive ways
that complement in situ conservation efforts. These are
1. maintenance of endangered species stock reserves that are safe-guarded against in situ catastrophes
2. genetic manipulations for small species populations threatened with inbreeding
3. studies of taxonomy, behaviour, physiology and genetics
4. aiding public familiarization with the species as a defence against apathy towards extinction for a species
shrouded in obscurity,
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CAPTIVE POPULATION/DISEASE WORKING GROUP
Members: S. C. Sharma, L. N. Acharjyo, M. V. Subba Rao, T, P. Vyas, B. Dutta Gupta, Bipul
Chakraborty, Rajeev Pawar
The Captive Population / Disease Working Group discussed captive management and disease on the first day
with Mr. S. C. Sharma facilitating, and disease on the second day with Dr. L. N. Acharjyo facilitating. Using
a list of zoos in India holding gharial provided by the Central Zoo Authority the working group discussed
management in these facilities. It was not possible to tell from the information available how many zoos had
been successful in breeding gharial. However, the Group felt that sufficient expertise exists about the rearing
of gharials in the captive rearing centres started under “Grow and Release” programme of the Indian Crocodile
Project. Captive breeding of gharials has been successful in one Indian zoo and one captive rearing centre.
The expertise available in these centres can be utilised for other centres also.
Zoos as well as the captive rearing centres could provide stock for reintroduction in wild if it is required.
Wildlife managers should intimate their exact demand well in advance so that an appropriate programme
can be organised. Zoos can fulfill the demand of other zoos if self-sustaining captive population is built up.
However, in order to build up a self-sustaining meta-population — both for filling the modest needs of zoos
for exhibition as well as the larger demand for supplementation, a coordinated approach for captive breeding
of this species has to be undertaken. A species coordinator may be appointed for the purpose by the Central
Zoo Authority.
On the basis of the assessment of the working group, the existing facilities now holding gharial have a
potential capacity of 4000 to 5000 gharial hatchlings for supplementation purposes, if renovation work to
improve the facilities is taken up. This includes changing of wire mesh, repairs of water pools, improvement
of water supply system, in some cases, expansion of facility, etc.
As some of the captive rearing facilities are not maintaining gharial in proper way it is recommended that
1. Minimum facilities for welfare of the animals should be provided at all zoos.
2. Zoos which are designated as captive breeding centres for gharial should construct their enclosure for
gharial as per the requirement of the species in the wild, such as deep pool, free flowing water (at least for
some hours of the day) and high sand banks for nesting and basking.
3. The zoos which can afford both spatial and financial improvements should construct nature-simulating
spacious enclosures for exhibition so that the public can be educated about the behaviour and biology of the
species and also form a positive image of the animal. In order to start a coordinated breeding programme, an
individual identification mark of gharial has to be done. This will make planned captive breeding possible.
A Studbook should be started with available gharials in zoos/gharial rearing centres. All the zoos/captive
rearing centres should maintain records indicating the origin of the individual/groups in order to facilitate
maintenance of genetic diversity of the captive population as well as those which are to be used for
supplementation in wild.
Moreover, as it has emerged from modelling exercises that introduction of more males may be required,
contemporary research has opened up possibilities of controlling the sex ratios of crocodilians produced
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through temperature controlled incubation. This technique should also be investigated through scientific
research in the case of gharial to make available a tool for gharial management in the wild through
supplementation if so required.
As it is not possible to determine the sex of the animal by the age at which they are normally reintroduced,
biotechnology laboratories may be consulted for a means of doing this.
There is no provision in Zoo Rules 1992 about the maintenance of reptiles in captivity. Therefore, the group
strongly recommends making provision in the Zoo Rules for providing minimum standards for the upkeep
of reptiles in general with special reference to gharial.
In some of the centres captive breeding of the gharial is already going on. It may not be necessary for such
centres to collect eggs from the wild for hatching. But those centres where successful breeding has not
occurred must depend on collection of eggs from wild to fulfil the requirements of the supplementation
programme.
Health and Husbandry
To ensure better survival and good health for animals the following husbandry recommendations are made:
a. Uninterrupted supply of clean fresh potable water must be ensured
b. Each pool should have good drainage system for effective cleaning.
c. As high mortality is observed during winter months, special care to provide warmth
to the hatchlings has to be taken up.
d. It has been generally seen that good quality fish is not supplied by the contractors for
the gharials and this affects the health and survival percentage in captivity. To overcome this,
a captive fish breeding/rearing centre, managed by fishery specialists should be set up near
every captive gharial breeding centre.
e. Each centre should have a small laboratory supported with qualified lab technician
and attendant for routine health checkup. There should be provision of visit of a veterinary
doctor for health monitoring of these animals regularly.
f. No dead animal of these centers should be disposed off without detailed post-mortem
examination. In case the diagnosis is not possible on post-mortem examination only
pathological studies of the materials collected during post-mortem examination should be
carried out with the help of nearest animal disease diagnostic laboratory.
g. One of the views expressed was that the gharial populations found in northern and
southern tributaries of river Ganges appears to be different from each other. It is suggested
to find out whether these two populations belong to two sub-species or strains or not with
the aid of DNA fingerprinting.
h. To avoid undue stress during transport and reduce the cost of transportation, the new proposed facility/
centres should be as near as possible to the release sites.
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i. The number of hatchlings to be reared should be decided strictly according to the
requirement of the stock intimated by the concerned authorities responsible for reintroduction programmes.
j. Entry of visitors inside the breeding/rearing enclosures should be prevented. Entry
of others connected with the management works should pass through foot bath containing disinfection lotion.
k. So far, the diseases recorded in gharial hatchlings are: Gastroenteritis, Hepatitis, prolapse of the cloaca, E.
coli infection, mouth canker, pneumonia, unabsorbed yolk, hunchback condition [calcium deficiency],
hypoglycemia syndrome, eye infection, bent neck condition, debility, and skin infection. It is recommended
to have detailed investigation with the help of disease diagnostic laboratories to come to definite conclusion
about the disease responsible for mortality.
l.. The data available on diseases and mortality pattern should be collected from all
captive rearing/breeding centres and compiled for distribution to the managers of these centres. This is likely
to help in reducing the incidence of disease/mortality.
m. The Group recommends having a training programme for zoo/captive rearing centre personnel in
management and health care of gharial in suitable institutions.
The captive breeding facility can also play a major role in educating the public about the importance of this
species/programme. A small interpretation centre near every breeding/ rearing centre is likely to fulfil this
objective. All the enclosures should have proper sign boards/plates depicting the date of hatching and other
important features highlighting the success of gharial conservation programme.
Rearing procedures for hatchlings should be standardised and these standards strictly maintained to insure
maximum production of gharial from eggs produced in captivity.
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INDIAN ZOO & OTHER CAPTIVE FACILITIES HOLDING GHARIAL
State/Zoological Park
M
F
U
Total
1. Nehru Zoological Park, Hyderabad, A. P.
0
0
2
2
2. Zoological Park, Itanagar, Arunachal Pradesh
0
0
2
2
3. Assam State Zoo, Guwahati, Assam
0
0
1
1
4. Jawaharlal Nehru Biological Park, Bokaro, Bihar
0
0
6
6
5. Sanjay Gandhi Biological Park, Patna, Bihar
0
0
12
12
6. National Zoological Park, Mathura Road, New Delhi
1
2
0
3
7. Kamla Nehru Zoological Garden, Ahmedabad, Gujarat
0
0
4
4
8. Sakkarbaug Zoo, Junagadh, Gujarat
1
2
0
3
9. Sayyaji Baug Zoo, Kareli Bagh, Baroda
0
3
0
3
10. Bannerghatta (National Park), Bangalore, Karnataka
1
2
0
3
11. Sri Chamarajendra Zoological Garden, Mysore, -do2
4
3
9
12. Thiruvananthapuram Zoo, Thiruvananthapuram, Kerala
1
1
0
2
13. Van Vihar National Park, Bhopal, M. P.
0
0
10
10
14. Kamla Nehru Prani Sangrahalaya, Indore, M. P.
0
0
5
5
15. Maitri Baag Zoo, Bhilai Steel Plant, Bhilai, M. P.
0
0
4
4
16. Gandhi Zoological Park, Gwalior, M. P.
0
0
4
4
17. Deori Gharial Rearing Centre, Morena, M. P.
0
0
156
156
18. Veermata Jijabai Bhosle Udyan Zoo, Bombay
0
0
6
6
19. Nandankanan Biological Park, Bhubaneshwar, Orissa
1
6
239
246
20. Mahendra Chaudhury Zoological Park, Chhat Bir
0
1
0
1
21. Jaipur Zoo, Jaipur, Rajasthan
1
3
0
4
22. Jodhpur Zoo, Jodhpur, Rajasthan
3
2
0
5
23. Udaipur Zoo, Udaipur, Rajasthan
0
0
2
2
24. Arignar Anna Zoological Park, Madras, T. N.
2
2
0
4
25. Madras Crocodile Bank Trust, Mamallapuram, T. N.
0
0
49
49
26. Mini Zoo, Kurukshetra, (Haryana), U. P.
1
2
0
3
27, Madras Snake Park Trust, Guindy, Madras, T. N.
0
0
6
6
28. Katerniaghat Sanctuary, Gharial Rehab Centre, U. P.
figures not available ---------------------------29. Kanpur Zoological Park, Kanpur, U.P.
0
0
5
5
30. Kukrail Crocodile Rehabilitation Centre, Lucknow
figures not available ---------------------------31. Zoological Garden, Alipore, Calcutta, W. Bengal
0
0
4
4
TOTAL : 31
14
30
520
564
* From Central Zoo Authority records, supplemented by R. J. Rao's list of rearing centres
FOREIGN ZOOS HOLDING GHARIAL
1) Zoo Atlanta, Atlanta, Georgia, USA
2) Honolulu Zoo, Honolulu, Hawaii., USA
3) St. Augustine Alligator Farm, Florida, USA
4) Silver Springs Park, Florida, U. S. A.
5) National Zoological Park, Washington D.C., USA
6) Singapore Zoological Garden, Singapore
7) San Antonio Zool. Gardens, San Antonio TX, USA
8) Sedge wick County Zoo, Wichita, Kansas, USA
9) Wildlife Conservation Park, Bronx, N.Y, USA
1
2
1
0
0
1
0
0
2
1
2
3
1
1
1
0
2
3
0
0
0
0
0
0
2
0
0
2
4
4
1
1
2
2
2
5
TOTAL:9
7
14
2
23
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EDUCATION AND AWARENESS
Introduction
It is generally accepted that the greatest failure of any conservation programme carried out — both in
India and in the world —in the recent past has been in the subject area of education and awareness. The
inability of agencies implementing conservation management strategies to take into confidence the local
people and involve them in activities being carried out, or — in many cases — even to compensate them
for the losses both potential and actual incurred by them as a result.
It is not only local people who have to be educated but different groups, from managers and financial
institutions, to policy makers and politicians. The budget given in any conservation project for promoting
education and awareness, if it exists at all, is never sufficient for carrying out the work in a proper manner.
Generally one brochure or handout will be made, often in a language that is not understood by the local
people and in insufficient quantities.
Sustained and systematic activities to educate people of all levels have to be undertaken if even a dent is
to be made in the problem.
In the case of gharial, its membership in the crocodilian order has given in an undeserved reputation for
ferocity and aggressiveness which needs to be countered. Also the number of accidental deaths of gharial
is sufficiently significant to justify an education campaign simply to communicate to people how to
recognize gharial and to avoid inadvertently killing them.
The mandate given to the Education and Awareness Group, therefore, was to create a comprehensive
Masterplan for Education and Awareness for Gharial, keeping in mind different target groups, variability
in problem areas as well as social, cultural and educational levels, and the paucity of funds for this work.
They were asked to create some material in the local language which can be made up and used in future
for gharial education programmes.
REPORT OF THE EDUCATION AND AWARENESS
Members: Dr. K. K. Tiwari, Facilitator, Dr. Tej Prakash Vyas, Recorder and Reporter, Dr. D. N.
Saksena, Dr. M. V. Subba Rao, Dr. Sudhakar Kar, Dr. B. K. Sahu, Dr. A. K. Sinha, Dr. R. K. Sinha, Dr.
R. Gupta, S. B. Mishra, C. M. Vyas, Rajeev Pawar, Sandeep Behera.
Education and awareness working group after thorough and careful deliberations recommends the
following major action programme
1. Identification of target groups
2. Actions to be taken to make them educated and aware for protection of Gharial with the help of action
oriented methodology
IDENTIFICATION OF TARGET GROUPS
Due consideration was given in identification of target groups to their degree of dependency on the
riverside resources and following target groups were identified.
1. Fishermen (anglers)
2. Riparian cultivators
3. Villages/panchayats/NGO’s/local bodies/towns along the river
4. Students and Teachers of local school/colleges and universities
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5. Law enforcing agencies
6. Industrialists
2. ACTION PLAN
2.1 FISHERMEN
ACTION PLAN FOR 2.1
I). Establish close contact and take them into confidence to collect basic information
about their problems and how Gharial affects them, then
II). Preparation and display of hoardings, handbills and other exhibits in local languages to educate the
people in fishermen’s villages.
2.1 METHODOLOGY FOR 2.1
i. Local students, volunteers of NGO’s and researchers will establish close contact and collect the current
status of Gharial killing, fishing practices, availability of fishes in the respective areas.
ii. Wildlife authority should put big hoardings in fisherman villages especially near identified habitats of
Gharial. The hoarding will display a good illustration or photo of Gharial with clear instructions for the
fishermen, “Do’s and Don’ts in local parlance.
iii. The local NGO’s / researchers/ and wildlife people will prepare booklets handbills with photographs of
Gharial in local parlance. Such handbills should be distributed at some regular intervals among the
fishermen and their cooperative societies, schools and panchayats. Handbills should contain some
information about promoting/protecting economic conditions of fishermen like promotion of ecotourism
and related activities.
2.2 RIPARIAN CULTIVATORS
ACTION PLAN FOR 2.2
i. Ban on agricultural/cultivation practices in the riparian zone specially where nesting/
basking grounds are located.
ii. Stop mining activities in riparian zone.
METHODOLOGY FOR 2.2
i. Demarcation of core zone and buffer zone in identified habitats of Gharial will be
done by local wildlife authorities and revenue people.
ii. The state mining departments should be approached by the concerned wildlife department to stop
any kind of sand/boulders/stone mining in the habitat area.
iii.Clear guidelines for the local cultivators should be given by the local NGO’s / researchers/ and
wildlife authorities about any agricultural practices in the netting zone and they should be told
about proper legislative action for the same.
iv.Hoarding should be displayed in local language with clear cut instructions for the farmers by the
local wildlife authorities.
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2.3 VILLAGE/PANCHAYAT/NGO/LOCAL BODIES/TOWNS
ACTION PLAN FOR 2.3
i.
To educate the people through awareness campaign
METHODOLOGY FOR 2.3
In every village/ panchayat in and around identified habitats a periodical/regular awareness campaign with
the help of various exhibits should be organized by local wildlife authorities, researchers and volunteers.
The exhibits would be audiovisuals, posters, charts, stickers, handbills, etc.
For Urban Areas along river bank: At least once a year a large exhibition cum awareness campaign should
be organised in towns for few days to a week on Gharial with the following exhibits.
- models of riverine ecosystem showing Gharial at the apex of food chain, biodiversity, museum specimen
of Gharial, if possible- charts, posters, stickers, handbills, Painting and essay writing competition on
conservation also should be organised at the same time. Prizes should also be distributed
-
Items like attractive calendars and gharial t-shirts to be made available on nominal cost
- On such occasions local cultural activists must be involved and arrange some drama, dance programme, mono
act play etc. and some well-known person could be invited to deliver popular talk on relevant topic
2.4 STUDENTS AND TEACHERS OF PRIMARY AND HIGHER SECONDARY SCHOOLS LOCAL SCHOOLS / COLLEGES AND UNIVERSITIES
ACTION PLAN FOR 2.4
- To start a nature club in every organisation
- To create awareness among the students and teachers for conservation of Gharial
- To involve NSS and NCC specially naval wing in conservation efforts of Gharial.
METHODOLOGY FOR 2.4
-Local wildlife authorities and researchers should visit each and every primary and high
school, college and university along the river and with the consultation of head of the
institution nature clubs should be formed to motivate the students.
-NSS coordinators/programme officers and associated naval officers of NCC should be
requested to motivate their volunteer/cadets for the protection of Gharial in their area.
- A regular awareness campaign with all possible exhibits should be organised for fishing community and to
such educational institutions at regular interval by the authorities of
such institutions, volunteers of the nature clubs and for this local wildlife authorities should take
initiative.
2.5 LAW ENFORCING AGENCIES
ACTION PLAN FOR 2.5
-Constitution of a board at block/district level
-To assess efficacy of implementation of Wildlife Protection Act in the area.
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-To create awareness among the authorities
METHODOLOGY FOR 2.5
-There should be provision under Act to constitute a monitoring board including host
officials/NGO’s/local researchers to enforce the implementation of the law.
- The NGO’s and researchers should collect information about the efficacy of implemen-tation of wildlife
protection act in the area and should bring it to the notice of local authorities through mass media of
communication.
2.6
INDUSTRIALISTS
Industrialists should be educated to desist from polluting and any other practices such as would affect water
quality and habitat of gharial. Promotional campaigns to encourage them to install operational pollution control
units could be taken up in the name of Ghar-ial conservation.
Industries can be educated by making them apart of the effort. Industries usually have an advertising budget and
can be convinced to sponsor educational materials such as brochures, handbills, stickers, etc. which promote
conservation of Gharial and carry the logo of the company.
3.0
TWENTIETH ANNIVERSARY OF CROCODILE PROJECT
The Government of India, the range states of Gharial, and the zoos and captive rearing centres holding gharial
should utilise the occasion of the 20th anniversary of the Croco-dile Project and Gharial Project to highlight the
success of the Project, the need to con-tinue protection of Gharial and the importance of Gharial to the
ecosystem.
Government of India should mark this anniversary in an elaborate manner, bringing out posters and brochures
reviewing the Project and suggesting future directions.
4.0 MODEL EDUCATIONAL MATERIAL
A sub-committee of the Education Group has designed a sticker/brochure which can be printed in a variety of
ways for different groups. A text in English and in Hindi was contributed and a slogan (Gharial is a mirror of
the health of our rivers) designed for a particular photograph. The English text of the sticker/brochure follows:
Gharial is a reptile which inhabits four major river systems, namely Indus, Ganges, Brahmaputra
and the Mahanadi river system in peninsular India. This reptile is an endangered species due to
commercial exploitation and habitat destruction. The Government of India has launched a “Grow
and Release” programme under the Indian Gharial Project, which celebrates its 20th anniversary
this year, 1995. This animal has been saved from total extinction by intervention of wildlife
managers to save the animal and its habitat which can only be done by larger participation, e.g. by
the local people, NGO’s and wildlife managers.
Let us save this animal, our pride.
5.0
EDUCATION SHOULD BE A MAJOR CONSERVATION ACTIVITY
The PHV A participants agreed that lack of public education had been a major lacunae in the Crocodile Conservation
Programme. It was felt by the Workshop that a major initiative should be directed towards specific target groups
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important to gharial conservation, such as fishermen and others who might have been affected by the Gharial
programme. Emphasis should be given on utility of gharial for sustaining the health of the river system and the
perilous consequences of its disappearance.
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PHVA FOR GHARlAL PARTICIPANT LIST
Dr.K.K.Tiwari
E-7/695, Arera Colony, Shahpura
Extension, Bhopal 462 016
Ph : 565 243, 565 535
Dr. Ishwar Dass
Chairman,State Committee for MP, WWF E1/154, Arera Colony, Shahpura Extension,
Bhopal 462 016
Ph: 563 854
Suresh Chugh
Dy. Director (Wildlife), GOI, MOE&F
New Delhi
Ph: 4363972(O)
S.C. Sharma
Member Secretary, Central Zoo Authority,
Barrack IV, Bikaner House Annexxe
Shahjahan Road, New Delhi
Ph: 381585; 386 012(O); 691 7139 (R)
Prof. M.V. Subba Rao
HOD of Environmental Sciences
Andhra University, Visak 530 003
Ph: (0891)554 871 Ext 290(O): 552 888
(R) Fax: (0891) 555 547
Mr. M.K. Mishra, l.FS.
Administrative Officer,
Indian Institute of Forest Management
Nehru Nagar, Bhopal, M. P.
Ph: 68122(O); 564 801 (R)
Mr. S.M. Hasan
Dy. Conservator of Forest (WL)
Vana Bhavan, Tulsi Nagar,
Bhopal 462 003
Ph: 550 942 (O); 521 056 (R)
Mr. CM. Vyas,
Asst. Conservator of Forests
I/C Great Indian Bustard Sanctuary
Karera Distt, Shivpuri, Uttar Pradesh
Dr. Rohtash Gupta
Professor, Dept. of Zoology
Kurukshetra University,
Kurukshetra 132 119
Ph: (01744) 30196 Ext. 197(O);
Dr. L.N. Acharjyo,
Sr. Veterinary Officer (Retd.)
House No. M- 71, Housing Board Colony
Baramunda, Bhubaneswar 751 003
Dr. Sudhakar Kar
Research Officer (Wildlife)
C/o Chief Wildlife Warden, Orissa
7 Shaheed.Nagar, Bhubaneswar 751 007
Mr. D. Basu
Gharial Centre, Kukrail Picnic Spot
P.O. CIMAP, Lucknow 226 015
Dr. H.C. Gupta
SDO Forest Suptt, Ken Gharial Sanctuary
Khajuraho
Mr. S.B. Mishra
National Chambal Sanctuary Project
Chakarnagar Forest Department
P.O. Chakarnagar, Etawah, U. P.
Ms. Fahmeeda Hanfee
Project Officer - TRAFFIC, WWF, India
172-B, Lodhi Estate, New Delhi 110 003
Dr. R.K. Sinha
Reader in. Zoology, Patna University
Patna, 800 005
Ph: (0612) 650 086 (R); 650 970(O)
Fax: (0612) 225 192
Dr. (Mrs.) R. Dalwani
Jt. Director, Ganga Project Directorate
MOE&F, New Delhi 110 003
Dr. M.R. Yadav
Reader in Zoology,
Turtle Research and Conservation Centre,
3/16, Muraitula, Ayodhya,
Faizabad 224 123 Ph: (05276) 2214 (R)
Dr. Tej Prakash Vyas
Professor and Head, P.O. Dept of Zool
Govt, P. G. College, Dhar 454 001. M. P.
Dr. A.K. Sinha
H.O.D., Zoology, DEI Deemed University
Dayalbagh, Agra 282 005
Ph: 350 772 (R)
Mr. B. Datta Gupta
Zoological Assistant, Zool. Survey of India,
27, Chowrangee Road, Calcutta 16
Mr. Bipul Chakraborty, Scientist
Central Zoo Authority, Bikaner House,
Barrack No. 4, Shahjahan Road, Delhi
Dr. .R.J. Rao
School of Studies in Zoology
Jiwaji University, Gwalior, M. P.
Ph: 340 463 (R)
Dr. R. K. Sharma
Research Assistant, National Chambal
Sanctuary, Deori, Morena
Dr. R.C. Sharma, CCF WL
Van Bhavan, Tulsinagar, Bhopal, M. P.
Dr. Ram Prasad,
Director General, MP Govt of Science and
Tech.,
Kisan Bhavan, Jail Road, Bhopal, M.P.
Mr. B.C. Choudhury
Scientist SE, Wildlife Institute of India
Chandrabani, Dehra Dun
Mr. N.C. Pant
D.F.O., Gwalior
Mr. R.L. Choudhury
D.F.O, Sheopur, MP
Mr. B.L. Verma
Son Gharial Sanctuary, Sidhi Dist., MP
Dr. Bhawani Kumar Sahu
Mr Sandeep Kumar Behera
Mr. Ravi Kant Pandit
Prof. R. Mathur
Prof. D.N. Saksena
Prof. B.G. Kapoor
Dr. A.K. Jain
Dr. O.P. Agarwal
Dr. A.O. Prakash
Dr. Sangeeta Shukla
Dr. I.K. Patro
Dr. (Mrs.) Nisha Patro
Mr. Suresh Bharadwaj
Mr. D.R.K. Mohan
Ms. Archana Johri
Ms. Munmun Chattopadhyay
all SOS in Zoology, Jiwaji University,
Gwalior
Ms. Sally Walker, Secretary/Convenor
Mr. Sanjay Molur, Programme Officer/
Facilitator
Dr. B.A. Daniel, Scientist
Zoo Outreach Organisation/CBSG, India
65 Bharati Colony, Peelamedu
Coimbatore 641 004
Ph: (0422) 571 087
Fax (0422) 573 269
Mr. Rajiv Pawar, SOS in Zoology
Jiwaji University, Gwalior, M. P.
Mr. Brij Bhushan Sharma
SOS in Zoology, Jiwaji University
Gwalior, M.P.
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P.H.V.A. FOR GHARIAL - REPORT
II. Supplementary material
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PROGRAMME
Inaugural Function
School of Studies in Zoology, Jiwaji University
& Organising Committee of
Population and Habitat Viability Assessment Workshop of Indian Gharial
16 January 1995 - 0915 -1030
Welcome Address
Professor R. Mathur
Head, School of Studies in Zoology, Jiwaji
University
Introductory Remarks
Dr. R. J. Rao
Principal Coordinator
Technical Remarks
Mr. S. C. Sharma
Secty., Central Zoo Authority
Mr. Suresh Chugh
Ministry Representative
Dy. Director, Ministry of
Environment & Forests
Ms. Sally Walker
CBSG Facilitator’s Remarks
Secty, Z.O.O., Convenor,
CBSG, India
Prof. P. S. Bisen
Patron's Comments
Vice Chancellor, Jiwaji University
Dr. Ram Prasad
Inaugural address
Director General, MPCST
Dr. R. C. Sharma
Presidential address
CCF, Wildlife, Forest Dept. of
Madhya Pradesh
Vote of Thanks
Dr. D. N. Saksena
Professor of Zoology
Tea followed by technical sessions
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P.H.V.A. FOR GHARIAL - REPORT
III. Reference Material
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POPULATION and HABITAT VIABILITY ANALYSIS WORKSHOPS
Objectives and Process
The PHVA workshop provides population viability assessments for each population of a species or
subspecies as decided in arranging the workshop. The assessment for each species will undertake an in depth
analysis of information on the life history, population dynamics, ecology, and population history of the
individual populations. Information on the demography, genetics, and environmental factors pertinent to
assessing the status of each population and its risk of extinction under current management scenarios and
perceived threats will be assembled in preparation for the PHVA and for the individual populations before and
during the workshop.
An important feature of the workshops is the elicitation of information from the experts that is not
readily available in published form yet which may of decisive importance in understanding the behavior of the
species in the wild. This information will provide the basis for constructing simulation models of each
population which will in a single model evaluate the deterministic and stochastic effects and interactions of
genetic, demographic, environmental, and catastrophic factors on the population dynamics and extinction risks.
The process of formulating information to put into the models requires that assumptions and the data available
to support the assumptions be made explicit. This process tends lead to consensus building on the biology of
the species, as currently known, and usually leads to a basic simulation model for the species that can serve as
for continuing discussion of management alternatives and adaptive management of the species or population as
new information is obtained. It in effect provides a means for conducting management programs as scientific
exercises with continuing evaluation of new information in a sufficiently timely manner to be of benefit to
adjusting management practices.
These workshop exercises are able to assist the formulation of management scenarios for the respective
species and evaluate their possible effects on reducing the risks of extinction. It is also possible through
sensitivity analyses to search for factors whose manipulation may have the greatest effect on the survival and
growth of the population(s). One can in effect rapidly explore a wide range of values for the parameters in
the model(s) to gain a picture of how the species might respond to changes in management. This approach
may also be used to assist in evaluating the information contribution of proposed and ongoing research studies
to the conservation management of the species.
12101 Johnny Cake Ridge Road, Apple Valley, MN 55124, USA tel. 612-431-9325 fax 612-432-2757 (home) 9801
Pillsbury Ave. S., Bloomington, MN 55420, USA tel. 612-888-7267 fax 612-888-5550
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PHVA Workshop Preparation
Information and Expertise
Short reviews and summaries of new information on topics of importance for conservation
management and recovery of the individual populations are also prepared during the workshop. Of
particular interest are topics addressing:
(1)
factors likely to have operated in the decline of the species or its failure to recover
with management and whether they are still important,
(2)
the need for molecular taxonomic, genetic heterozygosity, site specific adaptations,
and the effects of seed banks on the rate of loss of heterozygosity,
(3)
the role of disease, predation, and competition in the dynamics of the wild population,
in potential reintroductions or translocations, and in the location and management of captive
populations,
(4)
the possible role of inbreeding in the dynamics and management of the captive and wild
population(s),
(5)
the potential uses of reproductive technology for the conservation of the species whether
through genome banking or transfer of genetic material between subpopulations,
(6)
techniques for monitoring the status of the population during the management
manipulations to allow their evaluation and modification as new information is developed,
(7)
the possible need for meta population management for long term survival of the species,
(8)
formulation of quantitative genetic and demographic population goals for recovery of the
species and what level of management will be needed to achieve and maintain those goals,
(9)
cost estimates for each of the activities suggested for furthering conservation
management of the species.
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Preparation and Documentation Needs
Information to be included in briefing book:
1.
Bibliography - preferably complete as possible and either on disk or in clean copy that we can
scan into a computer file.
2.
Taxonornic description and most recent article(s) with information on systematic status
including status as a species, possible subspecies, and any geographically isolated populations.
3.
Molecular genetic articles and manuscripts including systematic, heterozygosity
evaluation, parentage studies, and population structure.
4.
Description of distribution with numbers (even crude estimates) with dates of information,
maps (1:250,000 or better if needed) with latitude and longitude coordinates.
5.
Protection status and protected areas with their population estimates. Location on maps.
Description of present and projected threats and rates of change. For example, growth rate (demographic
analysis) of local human populations and numerical estimates their use of resources (development plans)
from the habitat.
6.
Field studies - both published and unpublished agency and organization reports (with dates of
the field work). Habitat requirements, habitat status, projected changes in habitat. Information on reproduction,
mortality (from all causes), census and distribution particularly valuable. Is the species subject to controlled or
uncontrolled exploitation? Collecting?
7.
Life history information - particularly that useful for the modelling. Includes: size - stage
information, stage transitions, age of first reproduction, mean seed production and germination rates,
occurrence and survival of seed banks, life expectancy, stage mortalities, adult mortality, dispersal, and
seasonality of reproduction.
8.
Published or draft Recovery Plans (National or regional) for the wild population(s). Special
studies on habitat, reasons for decline, environmental fluctuations that affect reproduction and mortality, and
possible catastrophic events.
9.
Management master plans for the captive population and any genome banks.
11.
Color pictures (slides okay) of species in wild - suitable for use as cover of briefing book and
final PVA document.
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Plans for the Meeting:
1.
Dates and location. Who will organize the meeting place and take care of local
arrangements? Should provide living quarters and food for the 3 days in a location that minimizes outside
distractions. Plan for meeting and working rooms to be available for the evening as well as the day. Three
full days and evenings are needed for the workshop with arrival the day before and departure on the 4th
day.
2.
Average number of participants about 30 usually with a core group of about 15 responsible
for making presentations. Observers (up to 20) welcome if facilities available but their arrangements
should be their own responsibility. Essential that all with an interest in the species be informed of the
meeting. Participants to include: (1) all of the biologists with information on the species in the wild should
be invited and expected to present their data, (2) policy level managers in the agencies with management
responsibility, (3) NGOs that have participated in conservation efforts, (4) education and PR people for
local programs, (5) botanical garden or herbarium biologists with knowledge of the species, (6) experts in
plant population biology and needed areas of biological expertise and (7) local scientists with an interest
in the species.
3.
Preparation of briefing document.
4.
Funding (cost analysis available) - primarily for travel and per diem during the meeting,
preparation of briefing document and the PVA report, and some personnel costs. CBSG costs are for
preparation of the documents, completion of the modelling and report after the meeting, travel of 3-4
people, and their per diem. We estimate that each PHVA Workshop costs CBSG $10,000 to $15,000
depending upon the amount of work required in preparation and after the workshop to complete the
report.
5.
Preparation of agenda and securing of commitments to participate, supply
information, and make presentations needs to have one person responsible and to keep in close
contact with CBSG office on preparations.
6.
Meeting facilities need to include meeting room for group, break away areas, blackboard,
slide projector, overhead projector, electrical outlets for 3+ computers, printer (parallel port IBM
compatible), and photocopying to produce about 200-500 copies per day. Have food brought in for
lunches. Allow for working groups to meet at night.
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SSC MISSION
To preserve biological diversity by developing and executing programs to save, restore and wisely
manage species and their habitats.
PHVA WORKSHOPS Guidelines
Every idea or plan or belief about the Species can be examined and discussed
Everyone participates & no one dominates
Set aside (temporarily) all special agendas except saving the Species
Assume good intent
Yes and ...
Stick to our schedule ... begin and end promptly
Primary work will be conducted in sub-groups
Facilitator can call ‘timeout’
Agreements on recommendations by consensus
Plan to complete and review draft report by end of meeting
Adjust our process and schedule as needed to achieve our goals
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POPULATION AND HABITAT V1ABILITY ASSESSMENT
- CBSG/SSC/IUCN thanks the ‘Host Agency’ for the invitation to participate in this Workshop on
the conservation of the ‘SPECIES’.
- SSC MISSION: To preserve biological diversity by developing and executing programs to
save, restore and wisely manage species and their habitats.
- Captive Breeding Specialist Group (CBSG) works as a part of the IUCN Species Survival
Commission (SSC) to assist rescue of species.
- CBSG has conducted Population and Habitat Viability Assessment (PHVA) workshops
for >50 species in 22 countries at the request of host countries.
- Values of the Workshops are in:
* bringing together all groups responsible for the saving and management of
the species to build a consensus on actions needed for the recovery of the species;
*
bringing together experts whose knowledge may assist rescue of the species;
*
assembling current information on status of the species and the threats to its survival;
*
providing an objective assessment of the risk of extinction of the species based upon
current information;
*
using simulation models to test alternative management actions for rescue of the
species and its recovery;
*
producing an objective report which can be used as a basis for the policy and
implementation actions that are needed to save the species.
- These Workshops have helped chart a course for saving of many species; we hope that this
Workshop will be a help to our colleagues in their work to save the ‘Species’.
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PHVA DATA NEEDS
MAP OF POPULATION(S) DISTRIBUTION AND FRAGMENTATION CENSUS AND
CHANGES DURING PAST 10-50 YEARS
AVERAGE AGE OF FIRST REPRODUCTION (FEMALE & MALE) OLDEST AGE
(SENESCENCE)
MONOGAMOUS OR POLYGYNOUS
INBREEDING
CATASTROPHES & THREATS
ALL MALES IN BREEDING POOL?
MAXIMUM YOUNG PRODUCED PER YEAR
PROPORTION OF ADULT FEMALES REPRODUCING PER YEAR PROPORTION OF
YOUNG (LITTER/CLUTCH SIZES)
MORTALITY:
0-1
JUVENILES ADULT
FREQUENCY & SEVERITY OF CATASTROPHES
STARTING POPULATION SIZE (AGE DISTRIBUTION IF KNOWN)
CARRYING CAPACITY AND PROJECTED CHANGES
HARVESTS
SUPPLEMENTATION
ANNUAL RATES AND STANDARD DEVIATIONS IF POSSIBLE
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VORTEX
Simulation model of stochastic population change
Written by Robert Lacy
Chicago Zoological Park
Brookfield, IL 60513
Version 5.1, 13 April 1991
Stochastic simulation of population extinction
Life table analyses yield average long-term projections of population growth (or decline), but do not reveal
the fluctuations in population size that would result from variability in demographic processes. When a
population is small and isolated from other populations of nonspecific, these random fluctuations can lead to
extinction even of populations that have, on average, positive population growth. The VORTEX program
(earlier versions called SIMPOP and VORTICES) is a Monte Carlo simulation of demographic events in the
history of a population. Some of the algorithms in VORTEX were taken from a simulation program, SPGPC,
written in BASIC by James Grier of North Dakota State University (Grier 1980a, 1980b, Grier and Barclay
1988). Fluctuations in population size can result from any or all of several levels of stochastic (random) effects.
Demographic variation results from the probabilistic nature of birth and death processes. Thus, even if the
probability of an animal reproducing or dying is always constant, we expect that the actual proportion
reproducing or dying within any time interval to vary according to a binomial distribution with mean equal to
the probability of the event (p) and variance given by Vp = p * (1 - p) / N. Demographic variation is thus
intrinsic to the population and occurs in the simulation because birth and death events are determined by a
random process (with appropriate probabilities).
Environmental variation (EV) is the variation in the probabilities of reproduction and mortality that occur
because of changes in the environment on an annual basis (or other timescales). Thus, EV impacts all
individuals in the population simultaneously - changing the probabilities (means of the above binomial
distributions) of birth and death. The sources of EV are thus extrinsic to the population itself, due to weather,
predator and prey populations, parasite loads, etc.
VORTEX models population processes as discrete, sequential events, with probabilistic outcomes
determined by a pseudo-random number generator. VORTEX simulates birth and death processes and the
transmission of genes through the generations by generating random numbers to determine whether each
animal lives or dies, whether each adult female produces broods of size 0, or 1, or 2, or 3, or 4, or 5 during
each year, and which of the two alleles at a genetic locus are transmitted from each parent to each offspring.
Mortality and reproduction probabilities are sex-specific. Fecundity is assumed to be independent of age (after
an animal reaches reproductive age). Mortality rates are specified for each pre-reproductive age class and for
reproductive-age animals. The mating system can be specified to be either monogamous or polygynous. In
either case, the user can specify that only a subset of the adult male population is in the breeding pool (the
remainder being excluded perhaps by social factors). Those males in the breeding pool all have equal
probability of siring offspring.
Each simulation is started with a specified number of males and females of each pre-reproductive age
class, and a specified number of male and females of breeding age. Each animal in the initial population is
assigned two unique alleles at some hypothetical genetic locus, and the user specifies the severity of inbreeding
depression (expressed in the model as a loss of viability in inbred animals). The computer program simulates
and tracks the fate of each population, and outputs summary statistics on the probability of population
extinction over specified time intervals, the mean time to extinction of those simulated populations that went
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extinct, the mean size of populations not yet extinct, and the levels of genetic variation remaining in any
extant populations.
Extinction of a population (or meta-population) is defined in VORTEX as the absence of either sex. (In
some earlier versions of VORTEX, extinction was defined as the absence of both sexes.) Recolonization
occurs when a formerly extinct population once again has both sexes. Thus, a population would go “extinct” if
all females died, and would be recolonized if a female subsequently migrated into that population of males.
Populations lacking both sexes are not considered to be recolonized until at least one male and at least one
female have moved in.
A population carrying capacity is imposed by a probabilistic truncation of each age class if the population
size after breeding exceeds the specified carrying capacity. The program allows the user to model trends in the
carrying capacity, as linear increases or decreases across a specified numbers of years.
The user also has the option of modelling density dependence in reproductive rates. i.e., one can simulate
a population that responds to low density with increased (or decreased) breeding, or that decreases breeding as
the population approaches the carrying capacity of the habitat. To model density-dependent reproduction, the
user must enter the parameters (A, B, C, D, and E) of the following polynomial equation describing the
proportion of adult females breeding as a function of population size:
Proportion breeding = A + BN + CNN + DNNN + ENNNN,
in which N is total population size. Note that the parameter A is the proportion of adult females breeding at
minimal population sizes. A positive value for B will cause increasing reproduction with increasing population
sizes at the low end of the range. Parameters C, D, and E dominate the shape of the density dependence
function at increasingly higher population sizes. Any of the values can be set to zero (e.g., to model density
dependence as a quadratic equation, set D = E = 0). To determine the appropriate values for A through E, a user
would estimate the parameters that provide the best fit of the polynomial function to an observed (or
hypothetical) data set. Most good statistical packages have the capability of doing this. Although the
polynomial equation above may not match a desired density
dependence function (e.g., Logistic, Beverton-Holt, or Ricker functions), almost any density
dependence function can be closely approximated by a 4th-order polynomial. After
specifying the proportion of adult females breeding, in the form of the polynomial, the user is prompted
to input the percent of successfully breeding females that produce litter sizes of 1, 2, etc. It is important
to note that with density dependence, percents of females producing each size litter are expressed as
percents of those females breeding, and the user does not explicitly enter a percent of females producing
no offspring in an average year. (That value is given by the polynomial.)
In the absence of density dependence, the user must specify the percent of females failing to
breed, and the percents producing each litter size are percents of all breeding age females (as in earlier
versions of VORTEX). Read the prompts on the screen carefully as you enter data, and the distinction
should become clear. VORTEX models environmental variation simplistically (that is both the advantage
and disadvantage of simulation modelling), by selecting at the beginning of each year the population agespecific birth rates, age-specific death rates, and carrying capacity from distributions with means and
standard deviations specified by the user. EV in birth and death rates is simulated by sampling binomial
distributions, with the standard deviations specifying the annual fluctuations in probabilities of
reproduction and mortality. EV in carrying capacity is modelled by sampling a normal distribution. EV in
reproduction and EV in mortality can be specified to be acting independently or jointly (correlated in so
far as is possible for discrete binomial distributions).
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Unfortunately, rarely do we have sufficient field data to estimate the fluctuations in birth and death
rates, and in carrying capacity, for a wild population. (The population would have to be monitored for
long enough to separate, statistically, sampling error, demographic variation in the number of breeders
and deaths, and annual variation in the probabilities of these events.) Lacking any data on annual
variation, a user can try various values, or simply set EV = 0 to model the fate of the population in the
absence of any environmental variation.
VORTEX can model catastrophes, the extreme of environmental variation, as events that occur with
some specified probability and reduce survival and reproduction for one year. A catastrophe is determined
to occur if a randomly generated number between 0 and 1 is less than the probability of occurrence (i.e., a
binomial process is simulated). If a catastrophe occurs, the probability of breeding is multiplied by a
severity factor specified by the user. Similarly, the probability of surviving each age class is multiplied by
a severity factor specified by the user.
VORTEX also allows the user to supplement or harvest the population for any number of years in
each simulation. The numbers of immigrants and removals are specified by age and sex. VORTEX
outputs the observed rate of population growth (mean of N[t]/N[t-l]) separately for the years of
supplementation/harvest and for the years without such management, and allows for reporting of
extinction probabilities and population sizes at whatever time interval is desired (e.g., summary statistics
can be output at 5-year intervals in a 100-year simulation).
VORTEX can track multiple sub-populations, with user-specified migration among the units. (This
version of the program has previously been called VORTICES.) The migration rates are entered for each
pair of sub-populations as the proportion of animals in a sub-population that migrate to another subpopulation (equivalently, the probability that an animal in one migrates to the other) each year. VORTEX
outputs summary statistics on each subpopulation, and also on the meta-population. Because of migration
(and, possibly, supplementation), there is the potential for population recolonization after local
extinction. VORTEX tracks the time to first extinction, the time to recolonization, and the time to reextinction.
Overall, VORTEX simulates many of the complex levels of stochasticity that can affect a
population. Because it is a detailed model of population dynamics, it is not practical to examine all
possible factors and all interactions that may affect a population. It is therefore incumbent upon the user
to specify those parameters that can be estimated reasonably, to leave out of the model those that are
believed not to have a substantial impact on the population of interest, and to explore a range of possible
values for parameters that are potentially important but very imprecisely known.
VORTEX is,
however, a simplified model of the dynamics of populations. One of its artificialities is the lack of density
dependence of death rates except when the population exceeds the carrying capacity. Another is that
inbreeding depression is modelled as an effect on juvenile mortality only; inbreeding is optimistically
assumed not to effect adult survival or reproduction.
VORTEX accepts input either from the keyboard or from a data files. Whenever VORTEX is run with
keyboard entry of data, it creates a file called VORTEX.BAT that contains the input data, ready for
resubmission as a batch file. Thus, the simulation can be instantly rerun by using VORTEX. BAT as the
input file. By editing VORTEX.BAT, a few changes could easily be made to the input parameters before
rerunning VORTEX. Note that the file VORTEX.BAT is over-written each time that VORTEX is run.
Therefore, you should rename the batch file if you wish to save it for later use. By using data file input,
multiple simulations can be run while the computer is unattended. (Depending on the computer used, the
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simulations can be relatively quick - a few minutes for 100 runs — or very slow.) Output can be directed
to the screen or to a file for later printing. I would recommend that VORTEX only be used on a 80386 (or
faster) computer with a math co-processor. It should run on slower machines, but it might be hopelessly
slow.
The program can make use of any extended memory available on the computer (note: only extended,
not expanded, memory above 1MB will be used), and the extra memory will be necessary to run analyses
with the Heterosis inbreeding depression option on populations of greater than about 450 animals. To use
VORTEX with expanded memory, first run the program TUNE, which will customize the program EX286 (a
Dos Extender) for your computer. If TUNE hangs up DOS, simply re-boot and run it again (as often as is
necessary). This behavior of TUNE is normal and will not affect your computer. After TUNEing the Dos
Extender, ran EX286, and then finally ran VORTEX. TUNE needs to be run only once on your computer,
EX286 needs to be run (if VORTEX is to be used with extended memory) after each re-booting of the
computer. Note that EX286 might take extended memory away from other programs (in fact it is better to
disable any resident programs that use extended memory before running EX286); and it will release that
memory only after a re-boot. If you have another extended memory manager on your system (e.g.,
HIMEM.SYS), you will have to disable it before using EX286.
VORTEX uses lots of files and lots of buffers. Therefore, you may need to modify the CONFIG.SYS file
to include the lines
FILES=25
BUFFERS=25
in order to get the program to run.
VORTEX is not copy protected. Use it, distribute it, revise it, and expand upon it. I would appreciate
hearing of uses to which it is put, and of course I don’t mind acknowledgement for my efforts, James Grier
should also be acknowledged (for developing the program that was the base for VORTEX) any time that
VORTEX is cited.
A final caution: VORTEX is continually under revision. I cannot guarantee that it has no bugs that could
lead to erroneous results. It certainly does not model all aspects of population stochasticity, and some of its
components are simply and crudely represented. It can be a very useful tool for exploring the effects of random
variability on population persistence, but it should be used with due caution and an understanding of its
limitations.
References
Grier, J. 1980a. Ecology: A simulation model for small populations of animals.
Creative Computing 6:116-121.
Grier, J.W. 1980b. Modeling approaches to bald eagle population dynamics. Wildlife Society
Bulletin 8:316-322.
Grier, J.W. and J.H. Barclay. 1988. Dynamics of founder populations established by
reintroduction. Pages 689-701 in T.J. Cade, J.H. Enderson, C.G. Thelander, and
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C.M. White, eds. Peregrine Falcon Populations: Their Management and
Recovery. The Peregrine Fund, Boise, Idaho.
Lacy, R.C. Flesness, N.R., and Seal, U.S. 1989. Puerto Rican parrot population viability analysis.
Report to the U.S. Fish and Wildlife Service. Captive Breeding Specialist Group, Species
Survival Commission, IUCN, Apple Valley, Minnesota.
Lacy, R.C. and T.W. Clark. 1990. Population viability assessment of the eastern barred bandicoot in Victoria.
Pages 131-146 in T.W. Clark and J.H. Seebeck (eds.), The Management and Conservation of Small
Populations. Chicago Zoological Society, Brookfield, Illinois.
Lindenmayer, D.B., V.C. Thomas, R.C. Lacy, and T.W. Clark. 1991.
Population Viability Analysis (PVA): The concept and its applications, with a case study of Lead beater’s
Possum, Gymnobelideus leadbeateri McCoy. Report to the Forest and Timber Inquiry (Resource
Assessment Commission), Canberra, Australia. 170 pp.
Maguire, L.A., R.C. Lacy, R.J. Begg, and T.W. Clark. 1990. An analysis of alternative strategies for recovering
the eastern barred bandicoot in Victoria. Pages 147-164 in T.W. Clark and J.H. Seebeck (eds.). The
Management and Conservation of Small Populations. Chicago Zoological Society, Brookfield, Illinois.
Seal, U.S. and R.C. Lacy. 1989. Florida panther population viability analysis. Report to the U.S. Fish and
Wildlife Service. Captive Breeding Specialist Group, Species Survival Commission, IUCN, Apple
Valley, Minnesota.
Seal, U.S. and R.C. Lacy. 1990. Florida Key Deer (Odocoileus virginianus clavium) population viability
assessment. Report to the U.S. Fish and Wildlife Service. Captive Breeding Specialist Group, Species
Survival Commission, IUCN, Apple Valley, Minnesota.
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ISSUE 1.
MODELING
What is A Model?
One method for understanding the factors affecting the population extinction process is to use
population models. A model is a basic tool used to represent or describe, in a simplified and abstract form,
a particular process of interest. In the case of the PHVA, modelling is a tool that mimics the processes by
which populations propagate themselves from one year to the next.
Models can be very simple or extremely complex. Models may seem abstract, only academic, or
even threatening. However, we make use of and encounter models in our normal day-to-day activities.
Simple models that many of us encounter every day are symbols used in common signs. For example, the
male/female diagrams on toilet doors are in fact simple models used to summarize and simplify important
information. A more complicated day-to-day model is family financial planning. When we plan for financial
savings or budgets, we: 1) define a financial objective; 2) collect data on our financial situation; 3) analyze
the data under different scenarios using simplifying assumptions of real process; 4) evaluate different scenarios;
and 5) make a decision. We may do all this in our minds, without the aid of a computer or calculator, but we
nevertheless have preformed a modelling exercise to come to some conclusions. Population models are just
an extension of this process of compilation and analysis of data using a simplified version of real processes.
It is important to note that the purpose of the model is not intended to represent realistically and accurately
all the processes involved, but to simplify the process sufficiently to gain a better understanding.
A very simple population model may look like this;
————
Population
Size 1994
= 100
————
|
|
\/
+10 Births
+3 Immigrants
-7 Deaths
-2 Emigrants
|
|
\/
————
Population
Size 1995
= 104
————
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CBSG PHVA Process Manual
This simple process can be repeated year after year to give a basic idea of long-term changes in population
size. At a very basic level, all we need for a model of population projections are data on birth rates, mortality,
immigration, and emigration. This very simple model may be sufficient for some purposes. However, more
complex models that consider additional factors that affect population dynamics are more appropriate and
useful for the PHVA process.
What is A Simulation Model?
A stochastic population simulation model is a kind of model that attempts to incorporate the uncertainty,
randomness or unpredictability of life-history and environmental events into the modeling process. Events
whose occurrence is uncertain, unpredictable, and random are called stochastic. Most events in an animal’s
life have some level of uncertainty. For example, there usually is a 50/50 chance an individual is a male or
female and a certain probability that individual will live through one year to the next, mate, reproduce, and
produce an uncertain number of offspring. Although we cannot predict exactly what events an individual
will experience during its life, we may have a general idea of the range of possibilities for these various
events (e.g., on the average an individual may have a 90% chance of surviving from one year to the next, or
that litter sizes vary from 1 to 4), but individuals vary within that range. Similarly, environmental factors,
and their effect on the population process, are stochastic - they are not completely random, but their effects
are predictable within certain limits.
Simulation solutions are usually needed for complex models including several stochastic parameters. A
simulation model of an animal population mimics actual demographic and genetic events, such as deaths
and births, in an explicit time dimension. Both time steps and individuals are usually simulated as discrete
and finite. When stochasticity is included in a simulation model, each run may be a unique sequence of
events, with different end results in all runs. So, to be able to present both a reliable expected average result,
as well as an estimate of expected variations in the result, we need to run the simulation many times, often
several thousand times.
Events that are stochastic need to be described in terms of both their average value (mean) and their variance,
or standard deviation (a measure of the distribution which values can take around their mean). For example,
if litter size ranges from 1 to 5, average litter size may be about 3 and the variance around 1. When modelling
the effect of stochastic properties, both the average and variance need to be known.
The Vortex model incorporates factors with uncertain outcomes (stochastic factors) by randomly making a
decision about what will happen within the limits as specified by the variance associated with that factor. For
example, sex determination of a newborn is determined by the simple process of the computer “flipping a
coin.” Heads assigns one sex, tails the other. More complicated stochastic events, like the variation in survival
rates associated with fluctuations in the environment (both the survival rates and the effect of environment
have stochastic properties), are incorporated by the computer flipping multiple “biased” coins (those with
probabilities for heads and tails are not 50/50). The coin flipping process is achieved by the computer using
random number generators.
Because many of the processes in the population are stochastic, one run (simulation) of the model will result
in a different outcome than a second run. One run is no more accurate than another - they simply reflect
differences that might result from normal, expected variation in those stochastic factors that affect the
population’s dynamics. There are two levels of stochasticity incorporated throughout much of Vortex:
reproduction and mortality are inherently stochastic (like a coin toss) and also the probabilities of reproduction
and mortality vary over time (like a random selection of the coin to be tossed from a bag of variably biased
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coins). Thus the stochastic processes modelled by VORTEX includes both individual survival and annual
fluctuations in population survival rates (as distinct levels of stochasticity) and individual reproduction and
variable reproductive rates. Also (in contrast to the above) dispersal but not dispersal rates (or probability) is
stochastic in the VORTEX model. With respect to inbreeding, it is the individual mortality due to inbreeding
that is stochastic (i.e., some inbred individuals live, others die, but all have a higher probability of mortality
than do non-inbred individuals).
The same is true in real populations: two identical populations exposed to the same conditions will likely
have different projections. That is the nature of stochastic effects. One of the purposes of running the stochastic
model is to determine how much variation there might be around the average population projections. Therefore,
multiple model simulations (perhaps as many as several hundred) are needed to show the range, or distribution,
of possible outcomes that reflect the range of possible values affecting the population.
The processes in VORTEX that have stochastic or random components are:
Sex determination
Individual survival
Survival rates or probability
Reproduction
Reproductive rates or probability
Number of offspring
Dispersal
Gene transmission
Inbreeding induced mortality
Mate selection
Occurrence of catastrophes
Mortality and loss of reproduction
due to catastrophes
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Why Model?
There are a host of reasons for why simulation modeling is valuable for the PHVA process. The
primary advantages, of course, are to simulate scenarios and the impact of numerous variables on the
potential of population extinction. Interestingly, not all advantages are related to generating useful
management recommendations. The side-benefits are substantial.
•
Population modeling supports consensus and instills ownership and pride during the PHVA process.
As groups begin to appreciate the complexity of the problems, they have a tendency to take more
ownership of the process and the ultimate recommendations to achieve solutions.
•
Population modeling forces discussion on biological aspects and specification of assumptions, data,
and goals. The lack of sufficient data of useable quality rapidly becomes apparent and identifies
critical factors for further study (driving research), management, and monitoring. This not only
influences assumptions, but also the group’s goals.
•
Population modeling generates credibility by using technology that non-biologically oriented groups
can use to relate to population biology and the “real” problems. The acceptance of the computer as
a tool for performing repetitive tasks has led to a common ground for persons of diverse backgrounds.
•
Population modeling explicitly incorporates what we know about dynamics by allowing the
simultaneous examination of multiple factors and interactions - more than can be considered in
analytical models. The ability to alter these parameters in a systematic fashion allows testing a
multitude of scenarios that can guide adaptive management strategies.
•
Population modeling can be a neutral computer “game” that focuses attention while providing persons
of diverse agendas the opportunity to reach consensus on difficult issues.
•
Population modeling outcome can be of political value for people in governmental agencies by
providing support for perceived population trends and the need for action. It helps managers to
justify resource allocation for a program to their superiors and budgetary agencies as well as identify
areas for intensifying program efforts.
•
The VORTEX model analyzes a population in a stochastic and probabilistic fashion. It also makes
predictions that are testable in a scientific manner, lending more credibility to the process of using
population modeling tools.
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